Agree, file a JIRA issue.
My apologises, I successfully forget about the thread.
Quick search gave https://jira.jboss.org/jira/browse/JBSEAM-1656 which seems to be related to the problem I came across, but I believe the problem has the other reincarnation in the approach how Seam handles properties of session scoped components when passivating. I remember using Seam 2.1.A1 at the moment of posting the problem and 1656 had been fixed prior.
I filled a JIRA issue https://jira.jboss.org/jira/browse/JBSEAM-3384