[mikec557]

Update: in case this thread helps someone else.

I won't know until I get this other problem solved but I think I may have found the reason for the sporadic pump cycling. The current problem is a leak from the water heater "out" line. Sure, it obvious now if you look at the pics below. But at the time of the pump cycling I didn't see anything obvious on the water heater. But, I really didn't look at it. I looked everywhere else, the plumbing lines, the fixtures, etc.

So the take away from this is: don't overlook the two water heater connections when you're searching for a small leak/loss of pressure.