For about the past 4 months I've been hearing a rattle sound inside the car that sounds like it's coming from the back passenger seat. I thought maybe the seatback was not locked in at first from me laying the seats down, but once checked everything was in place and the sound is still there. I then thought maybe it was the cover that goes over the cargo area, but I took that out to see and the sound is still there. Almost sounds like it's in the framing of the car. I hear this mostly on secondary roads rather than on a highway that's typically smoother pavement. Anyone else had this issue? Dealer, of course, doesn't know what it is.