I am getting a sort of constant chirping/whistling noise comming form the rear of my XC. I thought it was the wind blowing across the hardbags but now it sounds like it is around the wheel area. Could it be the belt being loose? I thought it was only when I was on it but my wife told me she hears it all the time but I have the radio loud and it drowns it out. I am taking it for the 500 mile maintenance in the next day or two so I will have them check things out. Any thoughts?