Although APEX is different from all the other Alpines I think in regards to how it levels, here is the way mine does it. And although on a concrete pad type of site, I don't have to put out a jack blocks but I do, so the Hyd Jacks dont have to extend as far down, just the way I do it.
When we are ready to level the coach, I push a button on the Silverleaf (which is tied into the HWH leveling System-same thing different visual view) it dumps all the air, and as EM said counts 30 seconds elapsed time, then starts to auto-level the coach based on an (electronic level in the HWH control box). Once it's level were done, but we always check with a bubble level on the kitchen counter just to make sure. Sometimes it does not quite get it where I want it, so I usually raise the drivers side up a tad bit more, because I have two slides on that side which will pull the coach down a little if I don't.
Now to the original question, I don't dump when in storage, I leave the bags pumped up, and until my front bags were fixed so they do dump, one used to bleed off. I have not noticed this happening since the repair, but we have been on the road, and it has not been in storage. I will leave them pumped up once we get home so I can see if that bag looses air and if it does, I will spray some soap solution around and see if I can pinpoint where it's leaking. Like the fellow said, it's sitting on a rubber bag (think tire) and that is better than unlevel on the frame bumpers out of level. The air bags would take up some of the unlevelness of the site it sits in storage in I would hope. JMTCW.
Monty & Janet - 2007 Alpine APEX 40 MDTS
S/N - 75715 - Retired - Master Certified RV Tech