On the Guardian Screen, I noticed a RED HAM4 ISI.  Looking at the LOG, it said it had an ERROR from last Wed (4/9) after a WD Trip.  Here are the last few lines from Guardian's Log regarding the issue:

20140409_18:58:49.069 ISI_HAM4 W: EzcaError: Could not connect to channel (timeout=2s): H1:ISI-HAM4_WD_MON_STATE_INMON
20140409_18:58:49.090 ISI_HAM4 ERROR in state WATCHDOG_TRIPPED_FULL_SHUTDOWN. See log for more info. MODE=>LOAD to reset

I went to MODE, hit LOAD (HAM4 Guardian went white for 10s of seconds & then came back YELLOW), and then hit EXEC (now it's GREEN).