Clicked on Peons and was booted. Said already logged in

When I received the 10 Peons, random card pack and battle item just now in the mail, I clicked on the Peons and was booted with the game saying that I was already logged in. I am assuming this is a bug but would like to confirm. I was not logged in on any other computer.

Has anyone else seen this happen?

Proof that Santa Claus is real. Leaving presents and almost getting caught. You should leave a video cam next time.