I just purchased used 2008 cobalt coupe two weeks ago. Everything seems to be fine until I notice that when I release the brake, it make some whinning noise. Again, Just when I release the brake (not fully release, still tab on it a little bit). The noise come from driver's side and I think that it is inside the car. The weird thins is that it will be occur only when I start the engine. I can brake without another problem, just only this annoying noise. A car has just only 21500 Miles. Thank for your help.