Thanks for all the responses...appreciate them. The posts by PawPaw and time2roll might have the answers. That stimulated a memory that we had gone out to dinner, when we hooked up I had forgotten to turn on the hot water heater, did it as wife anticipating hot shower, we had not used the hot water and it wasn't too much longer when we noticed the leak....so, the scenario of hot water expanding without relief seems to fit (I hope so)...as I type, the water tank is heating up. I shall soon be checking it. Probably the rare occasion when I am hoping to see a leak....to solve the mystery.
