Also - UPS is NOT going to pass up a chance to bill more. Those guys can probably guess the weight +/- 2 pounds on their own. They will not go based on just the stamp on the box. GC may, however, have a deal where they post based on the average weight of a head. A lot easier than weighing ever individual head on the off chance that one is a little heavier - like the Mesa. figure that they probably move more Marshall MG heads than anything.
By the way - since the issue has been raised, and is making it's way to other places. YOU are telling the truth, right 9finger? I mean I don't really know you either....just kidding ; }
Might want to send a PM to Evan as a social heads up in any event.