We recently had a cabinet in our Interstate fall off the wall/ceiling. I chronicled the repair and you can find the thread
HERE.
We found the bedroom and galley cabinets in our van were not attached to ribs in the van. I wouldn't be surprised if Airstream used similar shoddy workmanship in trailers. The screw tightening (or lack of tightening) mentioned by turk123 may be similar to the problem we found in our van. Airstream had quite a large air gap between the cabinet and the wall. Yes, the screw could be turned (if you can call that tightening) but there was such a large air gap - sometimes as much as 3/8 of an inch or more, that the screw didn't really tighten against anything. We used shims behind the screws to fill the air gaps so the screws had a fighting chance of actually creating a compressive force between the cabinet and the wall.
In addition, the screws to the wall and ceiling may not be into a rib, they may simply be screwing into the interior skin. While that's okay, the cabinet will certainly be more secure if the screw is into the rib.