I had the same problem with shower. I told the dealership repair about as one on the other items that needed repair. They just recaulked it like Bama Rambler suggested. But now it is on the dealership if it did not work.
PS. Just make sure to drain your gray tank before going on a trip. I did not and pulled with a half tank of gray water.
2012 F150 Ecoboost, 3.55, tow package
2009 Flagstaff V-Lite 30WRLS
1982 16' Glastron Ski boat