in my experience most disc brakes sqeek. usually when cold. once they heat up a bit and teh pad warms up it will go away. now if is making a grinding noise than you know you have metal to metal. im not sure if you car has audible wear sensors on the brake pads or not. on alot of cars the brake pads have a piece of metal riveted to the pad. when the pad gets to say 10% life, the small piece of metal will begin to rub on the disc making a loud sqeeking sound. when that becomes constant it is time to get a brake job done.