Installed new rotors and brake pads on all four corners. Vacuum drained and replaced brake fluid, all factory parts. What a difference, braking was much improved. Several months later, the brakes seem to surge while braking downhill. Thought it might be air bubbles. My mechanic repeated the fluid drain process but no difference. The symptoms feel like warped rotor(s). We mic'ed all four - straight as an arrow, pads look good too. Anyone else experience this symptom shortly after new brake install? Cheers, from NorCal.