The club UPS may be failing.  Twice now it's misbehaved.  It switches to battery power (most likely corrrectly).  When the power returns seconds later it stays on battery power.  I've been home both times and managed to do an orderly shutdown of 5 VMs and one VM Host.  Then I power cycle the UPS and it works again. It now appears that the front panel display is getting intermittent.  If it happens one more time, I'll need to take action.  Exactly what action is TBD.