"Oh no love. The song has to be an original composition as well. I mean, it would be cheating if I just let you sing something you'd heard on the radio that reminded you of me or something like that." Though now she was curious, and she filed that away as a backup truth question - if there were any songs after her time that reminded him of her.
She assumed he was just playing for time; it was a bit of a challenge to come up with something off the top of one's head, especially under pressure. She was very eager to see what sprang to his mind though.