I think we might want to give him the benefit of the doubt... I mean, does it really matter? If he is lieing, then he just 1 person trying to save his characters reputation. If he isn't, so what? His cousin got onto his account while he was away. It isn't that big of a deal.
And about the 10 day thing, maybe, possibly, when he got home from his vacation, he didn't go straight to the computer to play Illarion.