Her first reply gained a nod of agreement even if his attention didn't waver from his food. It was obvious enough the response was aimed at her, he didn't see a reason to look at her too. "Mostly Marines," he elaborated, grateful that unlike some of his co-workers she at least seemed to know the meaning of boundaries. Not that he didn't like Chuck well enough (not that he would ever admit to as much out loud unless it was vital to survival), but the nerd tended to talk way more than Bourne preferred.
Her second comment gained nothing more than a grunt of acknowledgement, since he didn't have much to add.