Do guys stare at the girls whose their friend is interested in?

Is it normal for a friend of a guy who is interested in a girl to stare at the girl? This guy(Sean) keeps on staring at me and I don't know why. Even when he offers me snacks and I say, "oh no, thank you." he still stares. I know that his friend(Rafael) has a thing for me, but how come he(Sean) is staring at me? Even when we went to Rafael's house, he couldn't stop staring at me.