A good coherent lie, to appease Kitty's curiosity; half a truth, something hard to nail.

He set down the empty cup, building.

By the time he had filled his pipe and lit it he was ready.
Something bored up through the subconscious, however--a query.

Why hadn't he told her the plain truth at the start?
Wasn't on account of the drums.

He hadn't kept her in the dark because of the drums.