Mrs. Hudson is deliberately looking up to where John’s room is, she is not looking back at Sherlock’s room right behind her when she is shouting for the “boys” (John AND Sherlock) to come downstairs to deal with a client. Judging by the position of the sun in the sky in the previous shot it’s currently late morning, which indicates that the boys aren’t up yet because they should be hanging out in the living room having breakfast, like usual. What are you guys doing up there?? Must be sleeping in after staying up so late during their sleepover!