Did you try with 3.2.2 final release?
From the changelog:
When unJARing files, set the timestamp to the same value as the metadata in
the JAR file otherwise WARs containing files used by WebStart have faked timestamps
and are always re-downloaded by clients each time JBoss is restarted or the app is redeployed.
If its still not fixed, file a bug report.
Thank you very much.
All works correct in the final release 3.2.2.