Is he interested?

I feel like a child asking this, and in this relationship, I’m acting like one. I’m confused as to whether this guy I’m interested in is interested in me.

I’ve known him since freshman year of college (I’m a junior now) and some sparks flew freshman year, but I was incredibly shy at the time and we never really got to know each other.

He’s in a lot of my classes this year and I’m having trouble switching over from being that freshman I once was. Let’s see, here’s some evidence to suggest that he is interested-

- he asked me the second week of class if, when I got the time, he could paint me (we are both painting majors)
– lots of little flirty stuff has happened between us
– once late at night when we and a few other people were pulling an allnighter, he did tell me he liked me, but not in a way that I could take as being entirely serious
– he is very helpful and very generous
– he seems to light up when he sees me
– this month he randomly invited me over to his room for a beer, and was planning on making dinner and offered it to me, but I had to go. When I left, I gave him my number and told him to call me if he wanted to hang out.

But he hasn’t called. He’s been a little difficult lately, and kind of ignoring me. I can’t deal with mixed signals as I send them myself. Why wouldn’t he call? I don’t understand. I realize that the mature thing would be to just tell him I’m interested, but that is sometimes very difficult in process. What do you think?