Yes, can we please talk about this???
I love this tiny little moment because John IS NOT LISTENING TO MYCROFT. He absentmindedly agrees with whatever Mycroft says because he didn’t hear it at all. Y’all can tell what he was actually doing: checking out Sherlock as he walked away. Notice the lil lip lick as he’s saying “yeah”? Then he suddenly registers what Mycroft says and that no one is talking anymore, so he shakes himself back into the present.
John Watson, a goner for Sherlock Holmes from the start.
First he ignores sinister Mycroft in the wide, empty warehouse to check his texts from Sherlock, then AGAIN to check out his little brother, complete with lip licking. Love John Watson.