Just got a new set of brake pads and rotors installed about 2 months ago, the rotor used is the EBC GD slotted and drilled and the pads are Hawk HPS.

The brake works well but I can hear a grinding noise when braking at lower speed(below 20MPH I think) sometimes. The noise did get a little more frequent lately.

I know the Hawk HPS pads are not quiet but this is definitely a grinding type noise, not loud brake noise. No noise when I'm driving, braking really hard, or braking at high speed. Only when I apply a moderate amount of brake while trying to stop from a lower speed. And the brakes does work well despite the grinding noise. (I believe the noise is from the front wheels but not 100% sure.)

Anyone had similar experience with EBC GD rotors or Hawk HPS pads? Anything else that might cause this problem?