2007 X5 suspension noise

I am a new member to the BMW fam. I recently purchased a used 2007 X5 ~ 48000 miles. I have recently been hearing a noise sounding like it is coming from under my passenger side seat (under the car). It happens for about 5-10 seconds then quits. It is loud and obnoxious. It sounds as if something is pumping up but is struggling and is very loud (almost like a tire inflator) I have heard that it is the rear suspension leveling off. It only happens every now and then and MOST of the time it happens immediately once I put my car in park ( happened one other time while sitting in park for a few minutes). I am embarrassed of this noise, but I am assured it is the suspension and is very normal. Is this sound normal for rear suspension leveling off?

If it happens often you could have a slow leak on your rear suspension. The self leveling suspension uses air bladders to adjust the rear ride height. If the system has leak the compressor will have to turn on often to pump it back up.

For comparison, in the 2 months that I've owned my 2008 I've only heard the compressor come on once.