Hm, that's not really the question, is it? We're accustomed to seeing middle-aged singers playing teenagers (R & J, Butterfly, Lucia) -- but that doesn't alter the age of the character. What Lorna was doing was attempting to pin down Hanna's age, and I'd say she got it right. Otherwise Hanna would have to bury her husband of a few hours and then wait around for years until she was "mature" before taking off for Paris. That doesn't seem likely, does it? If she's no longer in her teens, she couldn't be more than in her early twenties.