[CREWZIN]

Lots of things that can cause vibration. Could be as easy as one of the wheel weights fell off or you picked up a nail in the tire and it's loosing pressure. If something came loose or broke on that trip it could be a number of different things but I wouldn't drive 350 miles back to the dealer before finding out exactly what it might be. Don't mean to scare you but with 42K miles, anything could be wearing out like a motor mount, tie rod end or wheel bearing. See if a local garage will check it out. Some will do it for free.