I have been seeing more dual pane windows with the seals pulled up into the window body. The heat generated due to outside storage seems to cause the seals to release from the window frame and get pulled up into the window area by the vacuum between the windows. I have seen this on all size windows. If I see one window seal pulled into the cavity, away from the frame, I usually see another.
When inspecting an RV, be sure to look closely at the edge of the window frame on the dual pane windows. There is no easy and inexpensive fix for the problem. The windows will have to be repaired or replaced as a unit. Repair cost can be $200 per window and up.
If a window begins or has a foggy appearance, the seal is the likely cause of the problem. Once the fog appears, it will get worse and is not likely that it will remain the same or improve.
The RV will have to be taken to a repair facility so the entire window frame can be removed and the glass seal replaced.