What's in a face?

Perhaps my face has turned pale while gasping for air after dashing up the subway stairs of Kyeongbock station to catch up a bus to my English class with two blind high school students. My kkaki coat was unbottoned and sways to the sides and my eyes were focused on the bus stop. Just few meters away from the bus stop, a male teenage Korean wearing a baseball cap, a sweater and denim pants saw me approaching and he gave me three bows. I didn't mind his head bowing but I realized on the third bow that it was intended for me. I smiled at him and return a bow, but he immediately turned his back and made a sign of a cross, among other Christians, the Roman Catholic way would do.

Was it my face that caused him to give me a bow? I don't know exactly what he was seeing in me. Was he seeing something behind me or accompanying me? I'm not pious or superstitious that I would claim that something supernatural happened but I would not dismiss any possibility that some people saw something other than me or in me.

But this is not a single occurence, of course, there are other instances that a total stranger gave me an intentional bow. In Korean culture, people just bow to strangers instead of saying "I'm sorry" or "excuse me" for stepping on your foot or has elbowed or pushed you. There must be something they see in my face which I'm not aware of. What could this be, familiarity, looking distinguished or friendliness?

What's in a face?