I just did a tested the TP valve, and it it releasing pressure (I can
hear water draining out of the pipe connected to it). There is no
leak, not a dribble. I also just checked all of the connections I can
see for leaks and I do not see any.

So, would you think the TP valve is weak if it works quickly and
properly to relieve pressure?

I'm a little concerned about needing to replace it since all the
paperwork states that this hot water heater (http://
waterheating.rheem.com/oem/catalogRes_detail.asp?id=21) is designed
specifically for MF homes. So, I'm not sure I can go to Home Depot
and just purchase any correctly sized HW heater.

So, when do I know if it needs to be replaced. When it explodes,
starts leaking, or stops providing hot water? I certainly don't want
to wait for option A to happen.

Thanks again for the replies,
Kim