Though she was anxious and worried for him, Rose did everything she could to keep the mood light. She didn't want him to know just how scared everyone had been. If she didn't keep her spirits up, she'd cry, and he didn't need to deal with that. Rose was used to being the strength and the backbone when possible, not the quivering mass she'd been the previous day.
"Well, think about it," she pointed out. "Anytime you're dealing with stress, it can affect your stomach, right? I know I had a rough time with food after I almost got fried by the sun. So who knows, maybe you just have a stronger stomach than me." That and he'd likely lost a load of blood and that might affect a tender stomach, but she couldn't bring herself to say it.