In case anyone is following this thread.....
The dealership did everything in their power to find out why this truck had the vibration. They put over $500 in parts in the truck, they out on OEM tires, used a PICO scope, and many other things, to no avail. In the end, they took the truck back and I now have a 2017 GMC Sierra SLE. I preferred the smaller truck, but the vibration was just too questionable to warrant keeping the truck.
Thanks to all who responded to my original post!