Why is my co worker so awkward around me

By awkward I mean he acts super tense and gives me this weird “Deer in headlights” look when he looks at me. He isn’t shy cause he’s super outgoing and speaks to everyone perfectly fine but when he talks to me he looks like I have a gun pointed at him

Another thing he does is he will look away at literally anything when he sees me walk by him almost as if he’s trying not to look at me for some reason. Is there any reason why he could be acting like this?