Couple things
1) Find a german specific independent repair shop, one that specializes in BMW.
2) It is a 10 year old high performance luxury SUV, there will always be little problems here and there to annoy you. I highly suggest you get into doing some repair work yourself if you don't already. This thing will nickel and dime you to death.
3) I don't have air suspension, but it could possibly be a leaky bag. Perhaps when they lifted the car up the full extension was too much for the aged bag. There are viable aftermarket solutions that many members here rave about. I believe
https://www.arnottindustries.com/ is the one.
4) If you go to the dealer, be prepared to bend over.