It's a little easier, with them both curled up in bed, for John to shift into the comforting mindset he adopts when Martin's just had a nightmare. Martin's dispelling exhalation and little shiver are familiar in that context, and John leans into it even though he knows the actual cause, in this case, was horribly real. He's had his breakdown; he doesn't want Martin suppressing his own distress for fear of setting him off again, and he'd rather offer comfort in exchange for what he's already received than just... pretend it's all settled.

"You don't have to apologize," he replies, stroking Martin's back and tucking his chin atop Martin's head. "I've got you."