What does it typically mean if you catch the same person looking at you frequently?

This guy who I don't know looks at me I think. One time, I was just walking and daydreaming, and I looked in his direction, and he was staring at me. Another day, I straightened my hair and with was died darker brown, and I saw him looking at me from afar, but I looked in the back of me to see if anyone else was there. Then today, his friend was talking to him from behind kind of, but he looked me in the eye "intensely", and there was no one else behind me. I said "intensely", because it looked as if eh was trying to have that look, but instead, it just looked weird, so I laughed. I do notice that he walks by me everyday at a certain time, but I really never thought anything of it until today. I know it could just be his usually route, but at the time he does it, there is no route you have to follow. You just go wherever.