I doubt it was a divert from Travis, as a pilot there I can tell you our last options are the Oakland or San Fran Airports. My guess is that there is a specific user that is shipping something on the plane. Oh and if you think a C17 dwarfs a 727, you should see what a C5 makes it look like!
It was in to bring in the support vehicles for Air Force 2, which came in on Saturday. Air Force 2 departed today (Monday) and another C-17 came in to move the support vehicles to the next location for the VP.