X-Post from Help & Support <Banned?>

My cousin who is in on leave was playing on my account last night and said I received an in-game message in yellow text saying something to the effect of: "Sorry but your account has been permanently banned...". After he told me that I logged out and was able to log back into my account and even join a game. I'm so confused as to what would have caused this? Any help would be appreciated.

Summoner Name: LionzEye