I would hesitate to agree with that, Dale. If on Auto-level, I've found the coach doesn't sink very far in one corner before the auxiliary pump briefly kicks it back up. Unless virtually all the air was dumped to begin with, and it wasn't very far off level from that, there shouldn't be any "wrinkles" in any bag. Unlike your trucks, the compressor on our coaches shouldn't let all the air leak out in Auto-level mode.
That said, I often dump quite a ways down prior to Auto-leveling in order to get the entry step as low as possible for the wife. That doesn't always work out, depending on the specific site, but even at the extremes I've not heard the described popping when the pump kicks in. Now it is common during the dump to hear the chassis pop here and there in protest on the way down toward the extremes; but not associated with the auxiliary compressor, nor even when air is let out in one corner by Auto-level as an alternative adjustment.
My guess would be the sound is related to the valve others mention.
-Joel
