Oddly enough I think I fixed my issue today. It turned out to be (from what I can tell so far) the lower rear portion of the plastic door panel contacting the door's inner skin. I cut a small lenght of soft rubber tune to make a "U" channel and put that between. Haven't heard the noise all day. We'll see how it does this weekend.
Its not strange that its only one side, mines just on the driver's side.
- Travis
Damn I wish I thought of that. My 2010 did had the same problem except it was more of a squeak which is why this thread didn't jog my memory. Make sure it isn't hitting the plastic kick panel trim too.