I have noticed that it has also happened to me the other way around, basically you go around and it happens automatically, you feel someone looking at you but there is not even any indication of it, not out of the corner of your eye or anything, it has simply happened to me with men and women and my thoughts on that Precise moment varies depending on the circumstance. It can be anything positive or negative. Just before it passes my head automatically turns in the direction of the person who is looking at me, I think it happens when someone concentrates more on their thoughts than on what they are really seeing at that moment.