We had something like this happen to us when we owned our '11 Montana. Just above the tandems the skirting was loose and letting go. Took it back to our dealer which was Pete's RV in Schererville IN, the looked at it and determined that 4 or 5 of the screws holding the metal skirting to the fiberglass section we're even screwed through the metal. No wonder it was falling. Like you, I figured this was clearly something Keystone "missed" on inspection and that no problem they would authorize Pete's complete the work CORRECTLY this time! Nope, Keystone said "too bad, so sad, you're on your own". We paid for the repair out of our pockets, not happy about that for sure.
All in all the Montana served us well but at one point we decided we wanted "quality". Now we have what we think is a better unit, more expensive but so far any little thing that has had to be addressed DRV has stepped up to the plate.
Dan