This could be related to http://jira.jboss.com/jira/browse/JBCLUSTER-42.
Some farm deployment problems (such as JBCLUSTER-42) were resolved for the 4.0.3 app server release. The 4.0.4 release has additional problems resolved.
Can you try to reproduce with 4.0.4 sp2?
Can you recreate with 4.0.4CR2? There is no service pack 2 release for 4.0.4. :)