Seam Framework - ConcurrentModificationException in Seam's FacesMessages

I'm getting a java.util.ConcurrentModificationException when invoking an action through a <a4j:commandLink>. The error cannot be reproduced every time, so I wasn't able to tie it to any particular sequence of events. My environment is Seam 2.1.1.GA on JBoss EAP 4.3 with Richfaces 3.2.2.SR1.

By the stacktrace (see below) it doesn't seem to be related to Richfaces, so I'm posting it here. If you guys have any tips on where to look for a cause or if there's already a solution out there, would greatly appreciate any guidance.

I found other references to java.util.ConcurrentModificationException issues in Seam, though they all cover different aspects; e.g. see https://jira.jboss.org/jira/browse/JBSEAM-3188. This particular one has to do with org.jboss.seam.faces.FacesMessages; so I'm not sure if this is a bug on our part or some misuse of Seam features.

Thanks in advance,

- Anton

java.util.ConcurrentModificationException
	at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:449)
	at java.util.AbstractList$Itr.next(AbstractList.java:420)
	at org.jboss.seam.international.StatusMessages.doRunTasks(StatusMessages.java:388)
	at org.jboss.seam.international.StatusMessages.runTasks(StatusMessages.java:379)
	at org.jboss.seam.faces.FacesMessages.afterPhase(FacesMessages.java:67)
	at org.jboss.seam.jsf.SeamPhaseListener.afterServletPhase(SeamPhaseListener.java:241)
	at org.jboss.seam.jsf.SeamPhaseListener.afterPhase(SeamPhaseListener.java:194)
	at com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175)
	at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114)
	at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:104)
	at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
	at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:522)
	at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:58)
	at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
	at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:177)
	at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:267)
	at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:380)
	at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:507)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
	at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
	at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
	at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:241)
	at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:437)
	at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:381)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
	at java.lang.Thread.run(Thread.java:595)