MAFs 00 Ws6

Ever since I drove my T/A home from the dealer I always heard a noise kinda sounds like a clicking but not, it is really hard to explain, but it sounds like it is coming from the rear. I can hear it when I am going around a right curve or just crusing with the car in netural. Does anyone have any idea what could be causing this noise? I have taken it to the dealer and they are like what noise I didn't hear anything. I know I didn't really explain the noise to well, but if this is a common noise than I am sure you will be able to identify with me. Thanks for the help..