Okay, Cal. I was going to say because there are more geese on one side, but figured I'd get laughed off the board.
I do wonder, though, if maybe it isn't do to which side the geese join the group on. That V can get awfully large across the back if you are the last one to join. If you were a goose and flew in from the east to join and the west side is shorter, would you want to fly across the width of the V to make the V perfect?:-)
Just my thoughts after my ridiculous guess earlier.