[Sherlock gives her quite the look for that one.]

What's a little fisticuffs between friends?

[He looks at the empty circle where the 'R' used to be emblazoned proudly.]

Kettle's just boiled. Don't agree with the Robin philosophy anymore? [He picks up a cup and hands it to her. She'll remember how to make it to her liking.] How long has it been?

[Hopefully not long enough that the line of questions is surprising.]