On a recent trip to Smoky Mountains, I noticed that the ribbed siding on my 10 year old Puma 28' camper was bowing out, like the wind from towing was pushing it out. I went to Ace and got some stainle...
I wouldn't worry too much about it. It's probably not getting air under it as much as the air moving over the outside is causing a low pressure area resulting in "lift" like an airplane wing. Also, my last TT did that just because the insulation was pushing it outward a bit. But it was like that just sitting there. I would make sure there's no cracks in the caulking anyplace but otherwise it should be OK.