It may actually be the bonus exp from rested exp. I often burn the rested exp on gathering/trading jobs. You get like... 50% more exp? But it only applies to mob kills not quest completions or whatever. I dunno if that's the biggest factor though because I remember chiming in on exp amount and i was sitting at 6mil where she was at 7mil. still. maybe we're killing a lot more mobs than I realize... so maybe it IS rested exp.