Suppose your rep is just over the borderline of a new privilege (eg. reviewing the edit queue), and you get downvoted, or downvote something yourself.
If the loss of rep brings you under the privilege requirement, do you lose the privilege?
I actually experienced it myself. Some guy serial-upvoted me past the 10,000 threshold (note: nobody asked him to do so). I could then see the deleted posts. He did it just for fun, so then he cancelled his upvotes, and I was unable to see those posts again (until I regained the rep more "legally").