2014 Limited Platinum here and I have noticed some noise in the back as well. I could be wrong but it seems to be from the drivers side rear. Like others its only on larger bumps and I only seem to hear it going slow. For example backing out of my driveway going over the curb to get onto the street. Its not a squeak, but more so like a rubbing sound. As if the tire is quickly brushing against the fender, but I cant imagine it would be. Mileage is at around 6K, cant remember the first time I have heard it but I would say atleast a few months now. Now that I think of it it may have started when the temps have gone down now that its winter. I will mention it to them at the 10K appointment, but besides that I would be curious to see if it happens when the temps go back up in the sprint time.
I have not got under the car yet to look things over, but I cant imagine being able see anything abnormal. Its probably shock related as someone mentioned above.