The trouble with big front windows...

RamblingSid

...seems to be that wind pressure during towing can force the outer skin to touch the inner skin and damage both of them.  Ours developed a small patch that looks a bit like condensation, but it is inside and on both surfaces. The dealer took one look and
said he would order a replacement.  The outer skin does seem, on pressing, to be much more flexible than any of the other windows.