Does he like me back?

It's really hard to tell because first of all, he had a gf, so it makes sense that he'd hide it if he does like me, and second, if that's the case, he's good at it. He's a pretty stoic guy. I'm as transparent as glass, whereas he's as transparent as a brick wall. Earlier this year, he uses to stand really close to me, look at me, and not really hide his friendliness, but I think a rumor got around that we like each other because his gf glared at me every time we saw each other for a while, and he quit. He still stands closer to me than most from time to time, but it's usually just to pick up homework or something like that. Maybe he's disguising it? I often see him looking around, his eyes flick to me, then looks away again. He seems to look at me a second longer than everything else, but it could all be in my head. I decided to test it once and stopped looking at him for a while, see if he reacted. I really think he was looking at me more and longer, but once again, what if I'm deluding myself? Then, about three days into my "test", he returned it and stopped looking at me at all, as if testing me himself. This was Monday, and Tuesday morning, I quit my "test" and coming into school, I saw him alone by his locker. I looked him straight in the eyes and smiled a little. His eyes flicked away, and then returned, and we maintained eye contact for 5 seconds, the longest we ever have. No one was around. If he's trying to hide his feelings for me, he didn't have to then. Later that day, when he came into class, I think I was the first person he looked at, but idk. Later that hour, when he didn't think I was looking at him, he glanced my direction. When I looked up, we had eye contact for a second or two before he looked away. Everything seemed back to normal today (Wed). Well, except for one thing. His friends were talking about what they were getting their gfs, and when they asked him, he said "I don't know" and dropped it immediately. Is it because I was there? Probably