My earliest memory has to be when I was five when I first started formally taking private violin lessons. I had learned from my mom before then. I just remember not myself so much but the violin teacher, who was a college student at the time. She was really tall and had long hair. She made my play the Suzuki book.
Maybe you this is your earliest memory because now that you are in college and you have repressed feelings for the girl who gave you violin lessons. Now that you yourself are in college, you think back about her and how she was pretty and if she was in college with you right now you'd make moves on her.
I agree that you are thinking of the college girl because you are now in college. As a young child, you look up to older people and now you are one of those "older people". It is interesting that you remember her as being pretty because usually you remember things as better than they were (not saying she wasn't actually pretty).