Never heard of such a thing in 20+ years of playing with bows... If anything I'd think a smaller/lighter peep would make it worse since the string would travel faster and oscilate more. Which might be exactly what you're seeing. You took weight off the string and increased the speed of your bow which is creating more energy/noise. Sounds like a classic case for one of Mean V's string dampers or at least some string leaches or cat whiskers.