I've got a 2001 A4 1.8T, and whenever I start it up, no matter what the temp is, I always here this...grinding or kind of like a clicking sound for the first few minutes. It usually goes away after a few minutes of the car running, and accelerating above ~50 mph. I feel like it could be the timing belt, because I've got about 82k miles on it and still have yet to perform the 80k service >.< but the fact that the sound goes away makes me think it's something else.

Any ideas on what it could be?