I think I’ve got something in my eye.
What I love most about this is that, like always, he turns to John because he doesn’t understand.
'John, did I do it wrong?'
You can see the character development in this, too, and how much it means to Sherlock to get it right, because he doesn’t just say ‘Not good?’ he says ‘Did I do it /wrong/?’
Because it’s important to Sherlock that he gets it /right/ for John and Mary.