am i old? am i mature?

I sometimes end up on the same bus as one of my aikido mates on the way to practice each week. We live about a block apart and walk the same way home after practice. On the bus this week, a friendly autistic savant decided to introduce himself to me, including part of his life history, birthdate and future travel plans. I was in a tolerant mood and decided not to ignore the intrusion into my conversation with my aikido pal and listen to his conversation. He proceeded to ask me my own birthdate, so he could tell me the day I was born on. I was curious to see if he could actually do that accurately, so I said, July, 27, 1978, revealing to everyone on the bus... my age. The savant quickly replied, "Oh, you were born on a Thursday then, and your next birthday will be on a Saturday, no Sunday, no....did you know I am going to visit my brother in NY..." I was impressed, but thought no more of it. Tonight on the bus though, my aikido pal suddenly brought up this past conversation and asked if I was really born in 1978. "You're really old then," he said. I couldn't help laughing. Old? I guess 27 is old to a 19 or 20 year old. I don't really feel old. He said he had me pegged for a 22-24 year old, which of course is very flattering, but makes me wonder about the level of maturity I project. I guess I should be asking, not am I old, but am I mature? After all my life experiences, traveling to other cultures and education, am I mature? hmmm....and do I want to be....