this is really starting to get annoying, but i'm hoping it's just the cold weather up north. Say i'm at a light, when I let off the brake to get on the gas, i hear and feel a quick rub, almost probably seems like a caliper sticking. i've done a full brakejob about 5k ago and currently have about 90k on it right now. Is there a certain time for the calipers or shims to crap out on me? could sticky calipers be the result of dirty brake fluid? Thanks for the input and Merry Christmas.