Not just the remark about the lipgloss, but the kiss and the touch and even the appearance of affection. The warmth of John's hands, the tug at his hair, hell just that he was being kissed. His pulse, under John's hands, slowed a little more with each stroke. Tension backed off a little. He forgot what they were doing - probably, brought his hands up to rest lightly against John's arm, just for the extra contact, and kissed him back, with every bit of warmth and affection and determination and everything that made Jack Jack.
It helped. It helped a lot. It helped in a way absolutely nothing else could have. It calmed him down, steadied him down, and narrowed everything down to John, and John's hands and John's mouth and right-now.