Take a look at this photo, where there are orange, blue, and pink teams in the same lobby.
http://img13.imageshack.us/img13/8533/wateb.png
The problem disappeared after we started playing, and I was apparently the only one who noticed it.
I suppose it was just a minor loading error.
If it matters, pink was a team color in the last game that played.
Actually not 3 teams but rather someone gets pink isntead of the right color.
The wrong color sometimes goes away after they change classes.