I noticed something similar when ours was new. I'd pull into a parking lot and get out, and notice one front side lower than the other. I don't know that it was 4 or 5 inches, but it was noticeable. I was also told by a dealership, where I'd pulled into for warranty service and parked, and thus pointed it out to them, that it was okay and normal. Okayyyy... I thought the air ride system would've kept side-to-side balanced, but I guess not necessarily. It is what it is when you shut off the ignition. The places it was noticeable happened to be lots that were sloped, so that affected things.
But yours happening on level sites is different; I would presume the ride height function to leave you relatively square up front - there is one ride height valve for the front and one for each back side. If it's catywampus, it actually could be a rear valve not functioning, leaving the right rear high, and consequently the front left low. At least if you air level within a half hour after parking, and the air-leveling or jack-leveling works properly, the fridge will be protected. If it was a leaky bag, you wouldn't stay level after setting up camp, or else the auxiliary pump would constantly run after auto-leveling to keep the low bag filled - but I don't know if your coach has auto-leveling.
If you're saying this happens after air-leveling in camp, then I don't know why a service manager would tell you that was normal, because it certainly isn't.
-Joel