It's my guess that they "posed" the question to see how you would respond...nothing more.
I am 45 and just graduated from Paramedic school and recently had my first EMS interview. The same type of question came up.
You should focus on what you bring to the position by being a little older, wiser and maybe more mature. You should focus on what you've been doing to stay in touch with EMS having not been active for 8 years. Don't let them rattle you.
Outside of interviews, I am asked the question often...by instructors, classmates, peers and...yes...even patients. I once had an 82YOF ask, "...at your age?".