I have an 07 Outback 2.5i, and I am getting a hum from the rear passenger brake area every time I press the brakes, even at very slow speeds. This does not sound like a break pad warn low sound. I pulled the wheel, and the exposed pad looks ok, and has some meat left so I think it's the caliper, but when I called to dealership they say they have not ordered a single one yet!!! What do others think? Has anyone had issues w/ there calipers? Thanks in advance for any help.