I'd give the following a shot, personally, before visiting a the dealership:
- use an air compressor w/ tight nozzle, or canned air, to blow around the knob
- give a firm but gentle push down in case the knob's stuck above the latching detent
- use a suction cup and give a gentle tug upward on the knob
That said, don't do anything unreasonable or too forceful else you may wind up w/ a warranty claim that'd be voided because of tampering. So, in any case, I'd document the evidence of the issue before you take any steps whatsoever just to have some degree of butt coverage.