Its a bug. I think there were some delay between you and the server, and you maybe dubbel clicked the delete button. So the server thought you deleted 2 PM's. And since V-bulletin cant go minus it went to the maximum instead.
It does that to the posts at least, if a user has 1 post and the mod delete that post then throws the thread to the garbage hes post count would go to the maximum instead of -1.
