I'm 49, soon to be 50, and I'm just finishing my MA in History (I'm ABT). This year I'm applying to PhD programs. I also teach World History at the undergraduate level.
I can tell you that most professors enjoy teaching "mature" or non-traditional students because they feel these students actually want to be in class learning something. Also, mature students get the work done without excuses and they bring real-world experience to the table. Don't be surprised to hear that no one is concerned about your age; you're the only one!
I have some additional advice about being employable after your degree: while you're a student, do everything you can to volunteer in whatever sector you are aiming to work in later. This will help you gain additional skills and experience to include in your CV later. Remember that potential employers often appreciate real-world experience that mature job applicants bring with them, just like professors appreciate it in the classroom.
One more really great thing is that so many of the people I come in contact with are younger than I am and this keeps me young too!
Best of luck to you
Kat