Dummy said:
Maybe those are vote transfers from old posts? Check "post history" of one of these posts and look for a reference to a parent post. If you find one, click it and see if it was deleted and has 0 votes.
Under normal circumstances, that wouldn't result in new potst showing on his favorite list. We only transfer the votes for replacements (where the old post and the replacement are identical)

If the child post somewhat differs from the parent post, the votes will not get transferred.

> At least when I am the one transferring.

Edit: Just noticed your comment ^^