2003 S55 AMG - Kneels when stopped
 

Hi, I have a new to me S55 that kneels down on the right side after being turned off for a couple of minutes. When I stop the car, I can here air pressure being released (like air-brakes). Suspension works great when running, and there doesn't seem to be any air-loss (you can't hear the pump constantly cycling).

Is my car in trouble, or just polite?