Hey Mark,
I've made a change which should address your situation. Now, each Lease has a unique identity, which is returned to ConnectionValidator. When the Lease changes, ConnectionValidator considers the connection to be broken.
I attached a jboss-remoting.jar to JBREM-1144 with the fix, if you want to give it a spin. It's a preview of 2.2.3.SP4, so it should be compatible with the rest of your system.
-Ron