2004 Mazda MPV Could my accident have caused my brake probl

Had my brakes serviced 9000 miles ago. Rear brake replace, front brakes were fine with 6/32 of pad.

Was at a stop light with brake pedal depressed and was hit from behind. Had body work done. Heard grinding noise took back to garage and was told that the caliper had been getting stuck in the closed position and was slowly leaking fluid and we had no pads left on the front.

My question is could this accident have damaged the calipers or is this just a coincidence? On average how many miles sould I expect out out 6/32 of pad?

Thanks for any insight