When I park my car and open the door and lift my butt off from the seat to get off my car, I hear a brief "squeaky" noise coming from the rear wheel. Specifically, it appears to be coming from the disk shroud behind the wheel itself. It's metallic and hollow. And when I close the door I hear it too, except of course, it's even more brief. What can it possibly causing this? It's very annoying. Anyone heard of this? TIA