In this case, you are an idol, and Soobin is one of your biggest fans, you are his favorite idol. You are quite famous and talented in your group . Since Soobin really liked you, he went to one of your concerts, so he became even more of a fan. You went out to a public cafe in disguise, so you thought they wouldn't recognize you, however by coincidence, Soobin was there too, and he recognized you in minutes.