I've had a girl do the EXACT same thing to me.
He's flattered that you have feelings for him. But he's just not into you like that. And you may never have given him that kind of vibe, so your confession of feelings for him totally caught him WAY off guard because it seems like this confession came completely out of nowhere.
There was a girl that I went to school with a while back. I had like one class with her, and we'd only talk in that class when a group of people were talking. Outside of class, we never really talked. She was pretty much a distant classmate from school.
Anyway, she told me that she had a HUGE crush on me and had for most of the year. I was SO totally flattered. It was so incredibly sweet, the things she said to me, I effing melted.
But I just wasn't into her like that. And it wasn't due to anything superficial. She wasn't bad looking either. She actually models now. I just know that we were two very different people with very different morals. I felt like any relationship I tried to establish would result in her being unhappy and either trying to change herself against her will for me, or vice versa. While I would love to be with someone who really admired me the way she did, I don't really think she knew what she would have been getting herself into by being with me and I think she grew to realize that as she got to know me a little better.
But I did tell her that we need to hang out more. And we did, a lot. I felt that if someone could find so much to like about me, they're someone I definitely someone I want to keep around and not just blow off. We became very good friends and we still hang out.
But basically, your boy's flattered, but doesn't see you as a potential love affair and probably won't. Sorry sweetie. But if you're willing to move beyond that, he'll make a great friend. Just think, a guy friend that won't fall for you.