Oh good. Sounds like a good outcome :)

I haven't read all the posts, but I wish to highlight the fact that someone could have deliberately hacked the boys account to be spiteful.
I have seen this with kids and facebook, and seen it totally destroy people, One time a friend (I teach martial arts and get to know students really well) and the boy was talking in chat on fb, and the girl (girlfriend) was nasty and horrible. After it hit the fan, he later found out it was someone posing as her, out to get him.

I would talk to the boy in particular and maybe the parents, first find out if he sent it or not (be nice about it, as your are being genuinely concerned with is an awesome thing!!!)! and I would be discussing fb and internet security as well with your dd. At such a young age (I have a miss12) they are very guliable and think everyone is genuinely who they say they are.
(the one reason why my kids still have a very limited access to the net, and they are 14 and 12, is that I don't trust other people, and even fb (i love facebook and nothing against it in particular) but mis use and malicious people can destroy people)