I've never seen this before. Certainly not normal. Maybe related to temperature change? I can't imagine the floor inflated from the wind of driving down the road.
If it happens again, I might poke it with a pin to see if it's under pressure or more of a heat expansion thing.
Otherwise, document it with the dealer (fotos via email) and have them check it next time it there.
2013 Winnebago 2301BH-Red
2012 Ram 2500 Megacab HO CTD