I just found [this on mSO][1]. To quote Jeff's answer


> This is correct. You are only allowed to cast one close or reopen vote
> on any given post, largely to prevent close/reopen wars involving the
> same cast of characters.

  [1]: http://meta.stackoverflow.com/questions/99141/bogus-you-have-already-voted-to-close-this-question-on-expired-votes