You should change your configuration to see where the problem is, see
http://community.jboss.org/wiki/CanJBossTellMeWhenIDontCloseAConnection
http://community.jboss.org/wiki/WhatDoesTheMessageDoYourOwnHousekeepingMean
it will give you hints where the code is not correct, and also is a workaround in production but it will cost a bit performance (not much).
You have to close Results, Statements and Connections in any case (e.g. in a finally block).
Also https://issues.jboss.org/browse/JBAS-8757 might be an issue.