How is college?

While waiting on an older woman who was with her daughter and grandchildren, her daughter asked,"How are you liking your first year of college?"
"College? I'm not in college..."
"You're not"
"No- I'm only a junior in highschool. I'm 16. The youngest person in the whole store."
We laughed and she apologized. I told her about being asked on Wednesday if I was married.
While fetching the left shoe for her mother, I was laughing in the stock room. My laughter died and so did my momentary happiness. Why do I seem so old? I hate being mature and aged. I'm youthful and love life?

What's going on?

Something's wrong. This isn't right. I feel it foreshadowing something and it honestly scares me.