The ‘Reserved By’ session message occurs on DPA’s, when the TPAM appliance ‘reserves’ a PSM session that the user initiates from their web browser. The expected behavior is that the user connects to that reserved session. In this case, firewalls were in probably in place preventing this normal behavior (but this can also occur for other connection failure attempts) preventing the session from connecting successfully and the sessions being left in a reserved state.
It’s not unusual to see a few of these sessions. If large numbers of ‘Reserved By’ sessions messages occur then this is not expected behavior.