I generally rough up any pad before installing on anything. Also, if you don't properly wear in the pads when they are new the same thing can happen. Generally proper wear in is done by going around 40 mph and gently slow the vehicle to a stop. Repeat a couple of times and your new brakes should be properly seated to the rotor. I also clean the rotor first with gas, mineral spirits, etc. prior to installation just in case there are deposits, grease, oil or whatever on them...