You were at their concert in Paris, you had the luck to be sitting on a seat pretty close to the stage. So you could see them up close. And they could see you and the people beside you too. During a few of their first songs, the members went to dance towards the fans around the stage. Yeosang went to dance his part near where you are. When the song ended, he made a pose for the end of the choreo and looked ahead, and the first thing he saw was you looking at him with a soft smile.