Anyone here an older brother to a sister? (long, serious)

[P.Dirty]

Background: I'm 21, in my final semester at NYU, and i've probably spoken to my sister a handful of times over the past 4 years. My sister is an 8th grader (13 yrs old) in Columbus, Ohio, a "star" on the basketball team, and an honor roll student. When ever I am home for Thanksgiving, Christmas, or a weekend over the summer, she always tries to give me a big hug, mostly to annoy me though I think, because she knows that I hate it when she does this. After I came back to NYC after Christmas, my sister IMed me for the first time ever and we've had a few conversations since.

Story: My sister IMs me today saying hi, and I start a small conversation with her. While doing so I look at her AIM profile. There is this very long quote that i'm assuming she got from some lyric or movie that I have not heard of about how she wants to be in love with some guy. And on top of that, there is this boy's name, yesterday's date, and the words "i love you". Now, I'm assuming that the boy passed her a note yesterday that said "check yes or no", and this is the day they have started to 'date'. When I saw this, I asked her to take out the words "i love you" out of her profile, because she obviously doesn't know what the words mean, and she repeatedly told me that she "wasn't going to do anything stupid". Now I was a kid a few years ago, and I remember saying "I'm not going to do anything stupid" to my parents, and then usually ended up doing something stupid. I told her that if she didn't take it out, that I was going to tell mom and dad (who would throw a [censored] fit).

I trust my sister to a certain degree, but at the same time, I feel like it's a little early for her to be saying i love you to a boy, and DEFINATELY too young to be doing anything that some of you pedophiles are thinking about right now.

What would you do if you were in my situation? Or what have you done being in this situation? Should I involve my parents in this (I'm assuming they haven't given her any birds and the bees speech since I never got that speech), or should I let my sister make her own decisions/mistakes in the matter?

And no I won't give you my sister's phone number or post pics.