You are correct that the cause for the behavior you're seeing is due to the "prn01" server being down during the "list jobs for print station" event. A user's server activity is remembered for 5 days (by default; you can change that behavior by modifying each server's <UserPrintActivityLifetime> value in the GlobalConfig.xml file). This is done to help keep the system resilient in the event that the Analyst (who maintains all user print notifications from its Collectors in its database) is unreachable.The time-out for the "list jobs" call to another Collector is, as you observed, 30 seconds. I do not know of any way to decrease this timer.
On another related topic: 15 seconds is a very slim time to react. In light of the response times when a failover must occur, I would suggest pushing this to a 35 second timer.