Do you have ANY aftermarket parts on or near the roof or front of your truck? If so, and the dealer is like my local dealer, they'll say something like "We can't troubleshoot that because you have that rack on top and the noise could be coming from that.
Completely stock except for the sealing strip — I actually just removed one on the right side for testing but haven't driven the vehicle yet to see if it made a difference. I also wonder if outside temperature is a factor. Last week was unusually cold in Seattle (low 30s, can you believe it?!
Do dealerships typically charge for investigating noise/rattle issues on vehicles still under warranty? The SA I spoke with during my oil change mentioned it would be $150/hr for diagnostics, which caught me off guard.