sounds like that, I'll have to look at the vote database to see where the vote came from.
..they probably voted at a site that is not shown to be logged ie not in the 4 voting sites we use.
or it was one of the sites we use but that site changed its name(I am pretty sure that is what has happened here), so its no longer shown in the Last voted at section. But there total votes are still accurate because there was a vote made under that username.
Which is really just minor bug that ain't even worth the time to fix as if they voted again it would work as normal.
Speaking of votes I fking hate Mojang this uuid crap, its going to make everything a mess and I have no idea how I will still run the cracked server or allow for cracked players to have votes as it won't be logged by username anymore :S
what a mess it will be.