Braking downhill noise

My wife’s car makes an odd noise when she puts on the brakes to stop at a red light on a hill. Flat surface or uphill, no funny noise. 2002 Chevy Cavalier 2 door LS, manual transmission. Should we be worried??

Sorry, I just re-read that, and it’s not clear. This noise ONLY happens (as far as I can tell) when she’s stopping at a red light going DOWNHILL.