Update............
Brought mine back last week and they agreed to reflash the software before taking anything apart.
Well, things went well for a week, no more "service 4wd message" but then yesterday I did get another one. The dealer has been more than fair, the truck runs well, no problems with the 4wd so I'll just wait until my next service call or oil change before bringing it back to further explore the message and codes.
Unless of course, if I really do encounter a 4wd problem.