You know what? I think i have the same problem! I've googled this so many times and couldn't find anyone else with something similar.

Mines a stock 2001 as well and it happens in winter and goes away when the weather gets warmer. I describe it as a low croaking sound from the right front whenever the nose of the car undips back up from braking hard or going over speed bumps. Another similar sound happens when I'm stopped at a stoplight and release the brakes quickly on the green. Does this sound like the same thing to you?

Anyone have ideas as to what's wrong? Last time I took it to the dealer it went away on that day, oddly enough. I have plenty of brake pads left and rotors should be fine.