Apparently all of Marcus' self-training from the war on remaining stoic in the face of anything abandoned him whenever he was confronted with Roger in any capacity, and he didn't even want to think about what was probably showing on his face at the younger man's words - disbelief and a spark of hope, most likely.
"Yes," he said quietly, forcing himself to stay relaxed even at the change in Roger's tone and sudden closeness, and after a brief pause added, "I wanted to make sure I wasn't hearing things."