I put in a new bathroom right by my water heater, about 25 ft of hot and cold pex line. Ever since The day I turned on the valves to do a leak test, I've had a very slow drip from my temperature pressure valve on my water heater. It's only a drip every few hours, creating very little water, but it has been consistently dripping. I'm wondering why this is happening. Any thoughts?
When you turned the water back on after your plumbing work you may have mobilized sediment in the tank or lines and this is interfering with the sealing of the TPV. You could briefly open the valve manually with the lever to try to clear it. After doing this it would take a while to see if the leak was stopped.
Of course, it could get stuck open or leak worse. Naturally you'd use a bucket under the relief outlet unless it goes directly into a drain or outside.
Perhaps you should have a new valve on hand when you start dealing with this. You might have to replace the TP relief valve.