I know what you're thinking: HE LIKES YOU SHERLOCK. But is it possible for him to think you're creepy for catching him looking at you all the time? (Like he thinks you've been looking at him the WHOLE time when in actuality, you just happened to catch him looking at you at the right time.)
He was checking you out, OR he was zoning out and just so happened to look at you at the same time lol. Confront him in a friendly way, be like "So I caught you staring at me a few times, what's up?" with giggles or something lol.