Who says you're too old to teach overseas? As long as you have the qualifications, I don't see anything stopping you. Besides, adults who learn a new language (for whatever reason) might feel more comfortable with someone around their age or older rather than someone who's young enough to be their son/daughter. I know age isn't a marker of skill, but there's this misconception in society that if two people have the same job and one of them is twenty years older than the other, that the older person has more experience.