Am I just overthinking this situation or?

Since the first day of highschool , this male teacher and I have been making akward eye contact everytime we see eachother. He's never been my teacher but recently since he found out what class I have he's been.coming to my class everyday and i always see him looking at me or he'll be talking to another teacher but when I walk by he glances at me. One day i saw him in the classroom so i decided to wait because i felt akward but after i came in he came back and stared at me. Another time I was passing by his classroom and he was about to go back into his classroom but once he saw me he stood at the door entrance. Also when I was walking with my guy friend he looked at me and then my guyfriend as if he was jealous. Anyway I saw a pic of him and this girl on social media and for whatver reason I feel kind of jealous.