According to the local dealer and listening for it on the numerous GCs and Vs driving by this is a very common "problem". They have tagged it "the crickets". 90% of the time it's the lousy bearings they use in the idler pulleys. I bought a 96 GC new in 95 and still own it. Just after the warranty expired "the crickets" appearred. I changed both pulleys and the "crickets" were gone for about a year. I asked the dealer how important it was to fix this because I sure as hell didn't want to make changing pulleys an annual event. They said "on a 10 scale about a 5". I have been living with the noise for 7 years now without a problem. It's up to you how serious you take it. I have learned to live with it. In your shoes I would do as said previously. If that doesn't work change the pullies. If that fixes it then you know what the cause is when it comes back. Cheers!