On my bus with the Key off, air is trapped at the Norgen valve. If it's leaning you definitely have a leak somewhere, I hate to say it but you need to look again. Pull the 2 drive tires and tag on that side, and soap everything in that circuit, Norgren, Ride Height Valve, Air Lines, Fittings, Bags etc. We have seen cases where the bag is leaking on the inside around the mount, this one is hard to detect. Leaks are something we all have and deal with, some folks are more picky than others, Some just dump the air when it's going to sit for a while so it won't lean.