I have a Rheem 41v50 50 gal gas water heater, and found a puddle under it and a lot of wet carpet in an adjoining room. It seems like the overflow valve may have tripped. I noticed that over the last week or two the hot water in the house seemed hotter than usual. This makes me think that the thermostat (or whatever you would call it) inside the water heater may be going... allowing the water to be overheated and the pressure to build up too much. Sound reasonable? If so (and considering the water heater is 10+ years old) is there a way to repair it or should I just get it replaced?

Thanks for any help and advice!

As long as the tank holds water I recommend repair and not replacement.
Since it's so inexpensive I would replace the T& P valve. I would also turn the thermostat back and if the water's still too hot I'd replace that also. Do you flush your heater out on a regular schedule? Let me know how you make out. Good luck, Tom