So I just watched Sherlock

So I caught the last episode of series two again on WHYY

Of course I cried

I was watching for clues, what could it be that we've missed? What is Moffat trying to say to us, where is it?

And then I think I heard it… I haven't had time to formulate a complete theory but I believe that it has something to do with what Sherlock said to John while they were talking on their mobile's while Sherlock was atop St Barts.

"It's what people do." Now, we've heard this phrase recounted numerous times through the series… I can clearly remember it being said when Sherlock is showing off in series two, episode two, when talking to Russell Tovey's character, about being 'show offs'. Is this time about saying goodbye, or is it about leaving notes?

I'm not sure where I'm going with this yet, but when I get the chance to sit down and think it all through I'm sure I'll get back to all of you…

What do you think?