I've had my S85 for a little over a year, and about have about 13,500 miles on it. Recently my engine has started making a buzzing sound, which sounds very similar to a cicada bug. It happens regularly, and is most noticeable at low speeds during light acceleration....like in a parking lot or neighborhood. Anyone else experience this 'cicada' buzzing....and possibly had it fixed? I have a service center appointment in about 2 weeks...but I'm mildly concerned that the techs will tell me it is 'normal' engine noise...or something like that. Thanks.