I don't think it is neccesary to inform player about such thing. Of course, this could be a very good feature in a real-time game, but in turn based game you have all the time in the world to analyze the situation.
I can tell you from my experience, that sometimes I also make mistakes and lose a game becuase of that. But in situations like these this feature wouldn't change a thing. If I'm not paying attention to the game, I wouldn't likely pay attention to this feature.