Yeah something is wrong with the barbarians.
I was at peace with them as calabim and in my current game the AI Bannor are apparently at peace with them, since the barbs ignore unprotected Bannor workers and march straight into my lands.
I guess it´s caused by getting a lair or barrow inside your civs culture radius, since that´s what happened in the calabim game. In the game with the Bannor there are tons of lizardmen coming, indicating that they have "captured" one of their ruins.
Oh and what´s up with the cost of the freak unit? Why would I ever build one if I can instead build 2 warriors and have hammers left over?
edit: Tried the barrow thing and couldn´t replicate it. Found another bug though: It seems as if all investment for a chance events are broken. Just got the horticulture event (+1 in the plot or chance for scientist and +3 health) and could choose the scientist directly.