Was the shower in use at the time of the leak? This past week end I noticed water leaking from under shower on our 21FBS. Shower had not been used yet that trip. My wife turned the hw heater on and some time after is when the water showed up. We did not have water hookup. I believe hw heater built up pressure and found weakest link to be fitting under shower stall. Will be contacting dealer to have them repair problem.