Ok - On the bottom of each door, at each end of the door is a complicated looking thing, which has a screw. This is a height adjustment screw, which raises up the door so the "air lock" actually works as it should. Mine did not when we purchased the coach, but adjusting up the door fixed the problem.
Once the "Yellow Handle" has been pulled which engages the parking/emergency brake, this releases the lock on the door and it can open especially if parked on a hill when one side of the coach is lower/higher than the other. Adjusting the screws mentioned above where the door has a tad but of resistance in rolling on the track will somewhat minimize this problem, but not eliminate it completely.
So I took some 1/2" PEX water pipe, and some pipe insulation for 1/2" pipe (don’t open up the insulation, slip the PEX inside the hole of the insulation) and put the PEX into the insulation after cutting it to the size of the track when the doors are both closed, and in travel, and now when stopping the door does not open until I take the little door stop out. It has not jumped out of the place I put it even going through CA as their roads have gotten real bad over the last few years. Montana also is pretty rough and it stayed in then as well. If you want to look it over we are going to be at DRR this year.
Monty & Janet - 2007 Alpine APEX 40 MDTS
S/N - 75715 - Retired - Master Certified RV Tech