Search Results: reading a smile

I have a coworker that is in a relationship, I think they've been together about a year and a half. He began the relationship shortly after meeting me. He definitely wasn't into me at first, because I tried to make conversation and he wasn't having it.. But over the past year, he seems to have developed some sort of interest in me. What type of interest, I can't tell.
He's a very shy, introverted man, that keeps to himself. He's not overtly flirtatious with me or anyone else, but he stares at me constantly. Everytime he comes into work, he looks at me first. When I look up and catch him, he either looks away quickly or keeps staring and will occasionally smile. He's started coming up to my desk to take some of my candy and say hi to me. But since he's pretty shy, he doesn't really talk that much. When we have talked, he's been nervous around me and rambles about random things. He also asks me a bunch of questions about my life, like where I live and what I'm interested in and stuff.

He's never mentioned his girlfriend to me, though I've overheard him talking about her to someone else. I know they went on a vacation together a few months ago, but when I asked him who he went with, he said his family.
I found his instagram and he seems very close with her mother.

Do you think he's interested in me? Or am I reading into it all too much?