This happened with me with my Stack Overflow account.
One day I got 500+ points and got the privilege of retagging; the same day I retagged one question, and got the Organizer badge.
Now I have a reputation lower than 500; while I did not get any down-votes, Stack Overflow took away my retag privilege, but I still have organizer badge.
How can this be explained?
Can anyone lose points without being down-voted, and without being notified, or even without getting a downward (red) bar in the reputation graph?
EDIT: I forgot to mention that I got 500+ reputation on February 2, and out of curiosity I tested retagging, and I got the badge. My profile doesn't show 1 red line, which is for bounty I set up (only 50 and doesn't account for losing more than 50).
I did get the badge on same day.
EDIT: @SO-loyal-people: If you are voting me down because I tried to get points by cheating, then you should also know that there are still several ways which SO is not able to detect. I posted this to know if SO has official doc and even implemented this. you know if you never try, You never know. and also down-votes matter if you are afraid of loosing privilege. So all the people who have put those insensible answers like "bounty is the reason" and kicking down-vote should realize this.