drain leaking in 2015 Winnebago

I did check the pressure relief valve and other things when the first drips appeared outside. First I checked the hot water heater as the drip was under it. My initial thought was I had not tightened the drain plug on the Atwood heater as it was drained for the cold November. Dry as could be. Then I thought perhaps the on/off switch for the shower sprayer was causing blow back. That had been a problem on another coach where the fastener was not quite tight. It did not leak until the flow was stopped. I removed the drawers and checked for water on the lines and nothing. I also reached under the pan and found no problem. Ironically the fitting had settled back in so was fine. We then traveled and it dripped again. This time we took the panel off and could see the fitting was out and from the length it was clear that it could move in and out with a little bump. We could have gone months. So the leak was inside so to speak as the water ran on to the fresh water tank and down on to the compartment containing hot water heater and found its way out between the decorative panel and hot water heater panel. When we were not moving some water sat in pockets on the compartment or tank and when we ran the washer and it would spin and shake a little it would move these pockets and drip. Of course that created feeling that washer was the issue so I also checked everything connected to washing machine-my first. This is why I posted as that short pipe could have continued to look ok if we had not been lucky and saw it when it had popped out. Thanks for the suggestions. I got a little smarter over this one. A long way to go.