Have 1600 miles on my rotors in a 10 month period. Lately my rear has started making noise on the initial engagement then it goes away but comes back. Pads were replace in Dec and have good meat left. Did a light sanding of the rotor and pads but it still came back. Did a pad swap with the front and sure enough the rear started making noise after 20 miles. Rotor is straight. LBS mechanic told me its time to replace the rotors. Any advice on what the check.