[Elecraft] Erratic KPA-1500 behavior

[Pete Smith N4ZR]

This morning, starting the CWT,  every few transmissions my amp was 
faulting with the indication of excessive driving power (~67 watts vs 33 
watts normally).  Each time, it would fault once, then operate normally 
for a dozen or so transmissions before the next fault. Then, about 10 
minutes into the hour, the faults stopped happening.  The K-3 showed 33 
watts throughout

I checked the KPA-1500 log, and all it shows is the "power input" 
fault.  What could be causing this erroneous indication of excessive 
drive?  A sticky relay?

-- 
73, Pete N4ZR