He's forgotten. He's encountered countless worlds and civilisations with different years and dating systems, his brains are probably slightly addled from being changed so often, his own history has been re-written more than once, plus he's a time-traveller so no calendar can help him. The chances are that he simply has no idea how old he really is, so he picked a number that felt right.
__________________
| (• ◡•)| (❍ᴥ❍ʋ)
|