Her request touches something deep inside of him. He does know about long memories and a special attentiveness paid toward the passage of time. And he also knows about the solitude that can so often overwhelm on certain days. He had quite a few of those certain days as he's certain Helen does.
His mind quickly wanders at the mention of the date, trying to place its significance until she mentions Ashley. He knows full well about Ashley. And her request makes his artificial heart warm to know that she would think highly enough of him to request his company on such a special day to her. He looks over to her again, slowing his steed to match the pace of hers. And he offers her a small smile, soft and genuine. "I would be delighted to spend that day with you and words could not express the honor I feel at your having asked me."