More than likely, the filler hose was in a bind inside. Vibration from use and towing, pushed it out. That's my guess.
And I have felt your warranty pain. They would've fix my hull. At least yours is fixable by shop.
That does not sound like a cheap fix either. Sorry for you trouble but great kudos to the dealer.
Thanks guys. I had just towed the rig 300 miles going on vacation, maybe the vibration did it. I don't know.
Time for another CSI award, number 1 in customer service!