Playing Turn after End of Game?

[76mm]

I had a new one today...I was playing a game and got back a turn in which my opponent had 58/54 (I had at least 20 points left). The weird thing was that this game was not in the "completed games" section, but in the "my turn" section, and I went on to play the turn, even though my opponent STARTED the turn 4 points over his point total. I think what happened was that my troops looted his camp the previous turn, but I thought it was odd that the game didn't end when that happened. Is this how it is supposed to work?