Would a girl do this, I don't know what to think? :)?

I was going through my back pack trying to find some writing utensils so I could draw and a certain paper fell out of one of my folders (It's summer now) and I remembered this. In comm. arts class at the end or so of third quarter of the year we got one of our quizzes back. When we handed them in we passed it to the end of the row (I was on the other end opposite from where we handed them down to) and I am in a row mostly of girls. None of which I would reject if they asked me out :)... Anyways when we got our quiz back I turned it over (I got a not so good of a grade so I was trying to hide it haha) and I saw that someone had written on the back of my paper "I love you" with a heart drawn by it! It looked like one of the girls in my row had scrawled that on my paper seeing that it was mine. I don't know what to think haha. It's been so long that I'm not going to interrogate anyone now, but I'm just a little confused and flattered :D... Would a girl do this? Would they mean it, or are they just messin' with mah head? Thanks! :)