The loss of fame is not, strictly speaking, a bug. To understand this, let me explain a little about how gaining fame works:
Each fame "event" has a certain number of points associated with it. When you achieve any particular such "event", the game records that you got it, and adds the number of points to your fame total.
Then, any later time that you get achieve that same event, the game checks, sees that you already have it, and doesn't give you anything.
Sometimes, though, due to one bug or other, the game adds extra points to your fame total. If this happens, the fame cleanup script (which runs either at the turn or around 10AM server time, depending on which set of scripts it belongs to—I don't recall offhand) will fix it when it goes through all your recorded fame "events", and adds up the points associated with them. If it gets a number that's different from your current fame total, it will replace your fame total with the number it got.
I hope that makes sense.
