Hi Again:
It could be caused by different composition brake materials if they have been replaced. Also, the slides on the calipers or pistons may be getting tight or corroded. Do you still have a good solid brake pedal? Does the brake pedal seem to be harder to push? If so, check for a small vacuum leak going to the brake booster. If nothing is found, you may want to have the brake booster vacuum checked.
Let me know if you have other questions.
Have a great Christmas!
Joe
Monday, December 22nd, 2008 AT 8:15 PM