Jack broke body contact - although it smarted, it would have looked worse not to - and regarded the Doctor with a cool expression that was (almost) completely genuine. The man had probably caught the flicker of a petulant lip-twitch, if he'd been lurking there for more than 10 seconds, but no matter. "Woulda thought you knew it's ungentlemanly to butt into a dance bein' done well."
His eyes glinted at the switch in tunes and drew down to that hand at the same time as his chin lifted upwards. Challenge accepted. He threw a wink at Booster, his expression momentarily transmuting. "Unfinished business. Won't keep you waiting long." Then he was once again strung with an attentiveness affected into casual poise, waiting on the Doctor's move.