my front disks have started to make noise from about 7mph to stop when i brake after a long time of not braking(like on highway or long road). Not really a high pitch squeek but more like a moan or a squeek like when you open a squeeky door really slow...front brakes were done 7months ago and the discs look a little dirty. Doesnt happen at every stop only when (i presume) they cool down during a long interval of not braking(highway or long road) since they dont make any noise at most stops. need to clean my discs? other ideas? ps since the brake job(quality parts knowing my grandfather) they havent made any noise till about two weeks ago.