mine does this too, my car is a mkv r32. cars only got 9000miles on it,
did take it to my local garage because my brakes were groaning too get em copper greased and ever since then it does it, when im reversing into my drive at slow speeds, is it because the pads are fitted back wrong, to tell you the truth never really noticed as i have my music on, but recently have noticed quite a bit, my car brakes spot on though, so not sure what it could be, any help is aprecaited