He looks at me then looks away quickly

This has been going on for almost a year and its driving me crazy. There is a guy that works at a store i am a regular at. At first I didnt really pay attention to him because he is a quiet, guy with a serious demeanor. Never smiles, doesnt talk unless he has to. Well I dont know how it began really but I noticed we were playing eye tag. Sometimes he would stop what he was doing and watch me pass by as I was leaving. One time I gave him a small smile as I passed by and looked down. (Im horrible with eye contact and he seems to hold his gaze) after that i noticed he would be in same areas of the store i was in. Orbiting, almost finding reasons to pass by me. He has always been respectful i think he felt like I was getting overwhelmed by the proximity (and i was feeling like that because I felt like he was making it obvious that he was going out of his way to be near) so he has backed off. I would try to make small talk with him at the register and he got tongue tied and blushed the first time and after that he would keep it to short answers. He was gone for a while but when he returned he seemed almost happy to see me. He greeted me with a hi, he seems to smile when I look up at him and he looks at me. And seems warmer with me in general even adding a "see you next time" But whenever im shopping I feel him looking at me. Several times ive caught him looking at me then looking away quickly. Or watching me from afar. Im curious what your thoughts are on this. I feel kind of embarrassed because he could probably say he feels like im looking at him too. But i feel like there is a weird energy between us that I cant figure out what it is HELP!!!😫😬