Chris, you don't say if you run with the side screens on or off. If it's with the screens on, it may be the lower rear padded part of the side screen rubbing on the rear three quarter bodywork panel behind the door. Mine does this. I use polish, the type that doesn't leave any white traces, on both the body panel and the black plastic of the side screen. If this works you may find it needs to be done at regular intervals, but it's worth it for the peace and quite!
