It could be the strings cables stretching causing the cam to over-rotate- along with the serving issue this could be increasing noise as the cable bottoms into the draw stop peg/region of the cam.

However, It's always difficult to diagnose "strange bow noises" online-I've seen a bazillion different things make a bazillion different noises and everyone describes things differently than someone else would-which only confuses everyone.

Your best bet is to go to your pro-shop/local range and have someone help you with narrowing down the issue.