Ive noticed that ever since I bought my bike last october that there was a slight noise coming from the front left rotor. It would only make the noise once every revolution. Now its getting worse. It sounds like a scrape, like metal on metal, but I still have about 3/8" left on the pad. I cant see any visible cracks, is the rotor just warped? If so, can I have a machine shop turn it like you can for cars? Id rather not spend 200 dollars on a new rotor.