Sherlock gets the call an hour after it's made. He's been busy in the bathroom. His routine is precise and can not be deviated from, not even if John insists that he can't hold it. Mrs. Hudson has an extra bathroom downstairs, after all.

Not that John's in the flat at the moment. He goes to Sarah's to pout now. It's not as if Sarah's let him into her bed yet.

Sherlock really has no opinion on that fact, one way or the other.

After checking his email and writing very nasty replies about how his time is being utterly wasted by the sheer idiocies of those requesting his attention, his eyes settle on his mobile. Mycroft.

You didn't leave a message. Are you planning on berating me further over my row with John?