Only Delta knows how York tends to frame how he views his life and his relationships, such as they are- the way he sees the world and tries to work out the best course of action at any given moment. For Sam to reach out and pick those words out of his mind-

D must've said something forever ago.

He can't find it in him to care, too pleased and too relieved to hear it. Voice low in the space between them, he murmurs against Sam's lips. "It's a constant as long as I can help it."