Quoted From Beefy:
Pull the wheels and inspect your work. Make sure all your bolts are tight, and make sure the pads aren’t flopping around in their spots. If the slide pin boots are torn, I think you can get replacements. It’s a good idea to do this to keep cr@p and moisture out of the pin area. Did you add a dab of anti sieze to the contact areas of the new pads? They could be sticking, and being knocked back once the car moves and the caliper releases. Just do a thorough check, and you will likely find your problem.
+1 and welcome to the forums!
I would also be checking the caliper bracket for excessive corrosion build up.
I would recommend torquing down all the fasteners you remove on the braking system.