How perceptive of you! Half of your prediction is correct. I'm not gonna say which half. :) As for Semi recognizing the bracelet, I don't think she did. I think she was just trying to figure out who the guy was that dropped it and belatedly recognized Seojoon. That bracelet though is special and they'll show why later. If you remember during the first episode, Suho was also looking at a bracelet at his desk and then he put it away. This is the first episode where they played Eunwoo's Love So Fine OST. You'll keep on hearing it from now on.