I recorded a video of it here:
It's definitely not the normal hissing and it occurs constantly/under all conditions (parked/at idle, when driving, etc). I did have it parked all winter in raised mode (to get it over snow hump next to garage) and hoping I didn't do any damage!
Anyone have any ideas?

 

The only thing it could is there is a leakage Airmatic system. You must check for codes in the Airmatic system with a scanner, code reader will not do.