It surprises Sam that Jack's so wordy and forthright, because he usually isn't very open about how he feels. But now and then, he'll have a moment where he gives her more than she expects, and it always catches her off guard. And sometimes, like now, she doesn't know what to say. She completes the run of wire she was making, finishes it off, then when she still doesn't have any appropriate words to respond with she just turns and hugs him, very tightly.