So, I've noticed this after leaving a tribe and entering/joining a new one.

I left a tribe (say tribe A) and joined a tribe (say tribe B).

I entered B's tribe house after a couple of rounds in survivor. Turns out I saw the chat from my previous tribemates from A after entering B's tribe house. This is either from the tribe chat or the tribe house chat but i'm guessing what i saw was from their(A's) tribehouse.

http://i60.tinypic.com/9px4sj.png

The text you see in the chat are sent from people from my previous tribe.

I'm not sure if this bug has been posted already, but just putting it out there.

-Regards

Okay, that's bug for sure O.o
I feel this, after understanding the reason, could be edited and get in use for a minigame...