Our '06 Dynasty has done that, almost since new, but very, very slowly. When we park for an extended period, with the leveling in service, it will re-level from time to time, due to the front left corner creeping down. When we park it in storage, without leveling, we always dump the bags to keep the coach from any chance of twisting as it creeps down.
I've been able to live with it, with truly minimal hassle, so I've just never taken the soap bottle and crawled under there to try and figure out where the leak might be. But I have become pretty well documented when it comes to the HWH system, which should be virtually identical to the system on your coach.
Attached is the air diagram for the air leveling system on our coaches. I hope that it helps. It is one page from the HWH operating manual, which you can download from their website, if you desire.