Smiling at him? You like him, but your body language doesn't say so. It's the first time he's ever felt unsure about his conclusion that he's not able to reach.

He would usually be able to gain much more with just a single look but now, he's afraid of making the wrong move, afraid of making you not want him back.

As per usual, he acts nonchalant and ignorant of his surroundings, but he watches you through the corner of his eye when you're interacting with John. He tries to ignore it when he hears you laugh at Watson's jokes, however, it doesn't work— he really can't.

It's his own ego that doesn't let him strike first, the one that's hindering him from letting you know how he feels. He does start bringing you to his investigations so you can truly get a feel for how he is. Fortunately, he tones down on being an asshole, so you don't get the wrong impression.