I've always heard that as well. I generally only run the half doors when I wheel, so the full doors don't spend much time hanging up there.How long have you hung the full doors? I was doing that for a bit but read that some people have seen stress cracks around the window frame and stopped (well, mostly since it's winter and they're on )
That said - I don't worry about it much. I've been hanging them up there periodically over the past 17 years, and I've had no issues.