I have been missing. [Said with a slight frown.] And I haven't hit my head. That would be too easy.

[Yeah, about that whole pulse thing... Sherlock knows what John intends to do, and he sits back again and casually folds his arms across his chest like it's what he intended to do anyway.]

It has been four days, John, but you came in behaving as though you'd only just stepped out to the grocery and I'd been here the whole time. Strange, isn't it? I've no explanation for that yet.