Sherlock called John at the end, instead of texting.
And Moffat said that Sherlock did something very out of character that everyone is missing. And we know that Sherlock prefers to text.
And now there’s this picture of John with some sort of hearing device in his ear while on the phone with Sherlock.

THIS HAS TO MEAN SOMETHING, RIGHT?
Someone please figure this out for me…
Source for the picture: http://ohheyitshanna.tumblr.com/post/17673958006
(Source: ohheyitshanna)