Hi Sounds like either the pads are moving in their slots or the caliper gets a bit sticky. Do you hear it only when reversing out of the garage? or driving forward? If you reverse in to the garage the calipers move slightly in their normal seating to the opposite direction, so when you then drive out they move back. If that makes sense :) Or the caliper is sticky and you may need to have then taken apart and cleaned. The sliders can corrode. If at any point when driving you feed a judder when driving then this can be caused by sticky calipers heating up the disks. At this point you should stop driving.