How come a question got closed by 3 votes rather than 5?

This question: Infinite-dimensional translation-invariant measure is closed with the message:

closed as exact duplicate by t.b., cardinal, Willie Wong♦ 1 hour ago

That's 3 votes, but the FAQ says:

When a question reaches 5 close votes, it is marked as closed

• If there have been $k$ votes, then the moderator's vote counts for $5-k$. I.e., moderator votes are always final. Similarly, a moderator's vote to open, delete, or undelete are final. If a moderator flags a comment as offensive it is automatically deleted. I don't have a reference handy. – Jonas Meyer Jul 6 '12 at 14:53