This question had 4 close votes(as noted by me in the comments) on 03/07/12. Now it has none. Did a moderator close/unclose to clear the votes? Or how else can they be removed? Why was this done? I don't see any note from a moderator or others if this was an action taken by someone. Maybe after a certain time they get cancelled if the required 5 are not voted?
Close votes age away and expire as part of a regular process. A close vote will expire after four days.
However, if the question has less than 100 views, the close votes will not age until it crosses that 100 views threshold.
For more details, see this.
You can only cast a single close vote and a single reopen vote per question.