There's a lot of good feedback so far. I should look for a way to
pressure test the hot water lines in the house. Since I'm out in the
county I would think that I'd hear my water pump running at night if it
was a water leak. I'm not sure if there's a way to log the duty cycle.

Do you think it'd be worth while to see how much gas is used by the
water heater on a per minute basis? Maybe I could do the same test on
a different water heater (friends) and compare the results. I'm
guessing if I drain all the hot water and fill with cold I can time the
refresh cycle to get a therm per minute number for each water heater.
It'd also be good to time the refreash cycle.

I'm going to look for a date of manufacture on the water heater tonight
and if it's old enough I might just kick it to the curb... but I'll
wait until with weekend's "leak" test in hopes of finding another load.