Excessive number of log entries 'this session has been closed'

From the logs; it appears that this message is logged very often after logging out.

2010-04-22 12:32:36,198 ERROR [TP-Processor1] org.hippoecm.frontend.model.JcrItemModel - this session has been closed
javax.jcr.RepositoryException: this session has been closed
at org.apache.jackrabbit.core.SessionImpl.sanityCheck(SessionImpl.java:381)
at org.apache.jackrabbit.core.ItemImpl.sanityCheck(ItemImpl.java:137)
at org.apache.jackrabbit.core.ItemImpl.getPath(ItemImpl.java:1270)
at org.hippoecm.repository.decorating.ItemDecorator.getPath(ItemDecorator.java:91)
at org.hippoecm.repository.decorating.checked.ItemDecorator.getPath(ItemDecorator.java:113)
at org.hippoecm.frontend.model.JcrItemModel.getPath(JcrItemModel.java:91)
at org.hippoecm.frontend.model.tree.ObservableTreeModel.lookup(ObservableTreeModel.java:85)
at org.hippoecm.frontend.model.tree.JcrTreeModel.lookup(JcrTreeModel.java:109)
at org.hippoecm.frontend.model.tree.JcrTreeModel.newTreeModelEvent(JcrTreeModel.java:80)
at org.hippoecm.frontend.model.tree.JcrTreeModel.onEvent(JcrTreeModel.java:63)
at org.hippoecm.frontend.model.event.ObservableRegistry$ObservationContext.notifyObservers(ObservableRegistry.java:77)
at org.hippoecm.frontend.model.tree.ObservableTreeModel$1.notifyObservers(ObservableTreeModel.java:130)
at org.hippoecm.frontend.model.event.JcrEventListener.onEvent(JcrEventListener.java:64)
at org.hippoecm.frontend.JcrObservationManager$JcrListener.process(JcrObservationManager.java:647)
at org.hippoecm.frontend.JcrObservationManager.processEvents(JcrObservationManager.java:1057)
at org.hippoecm.frontend.Home.processEvents(Home.java:148)
at org.hippoecm.frontend.PluginRequestCycleProcessor.processEvents(PluginRequestCycleProcessor.java:40)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1250)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1329)