Sounds like a caliper sticking, I would have it checked out if your not able to do it yourself. For me it was just gunked up slide pins which I took care of myself on my 2001 Knight. I found that in heavy traffic I just did not try to keep up with the flow and coasted a lot of times a few mph lower then everyone else. Yeah it lead to more people pulling in front of me, but everyone seemed to be aware that I take more space to stop. That and random use of exhaust brake on downhill grades (limited use but helpful.) reduced my overall braking needs.