Originally Posted by BGTV8

Could be a small stone or other debris between the brake backing plate and the rotor.

If you are not confident enough to jack the car, remove the wheel, support the vehicle with a jack-stand and inspect the car yourself, take it to a dealer and give them the opportunity to separate you from your hard-earned cash ...

A small stone or other road debris is the most likely explanation given that this occurs without using the brakes.