People instantly look away when they see me?

There were 4 people who do it, 2 are guys 2 are girls, one of the girls knows me and Iv talked to her a few times, then the for the 2 guys I know both of them and rarely talk to them unless they are asking me something. The other girl I didn't even know but she did it too. I also do not look at them directly but I see it in the corner of my eye and I am the one who is shy not them. All of them do it fast though as if its a reflex or something.