The hitch in his voice told the story.
Catherine hadn't stopped to think about the relationship Grissom had told them about. Her first priority was to get Sara back. But when she and Grissom had found the unfortunate hiker in the dessert and heard Grissom question the situation Sara was in, she was forced to think about the relationship Sara and Grissom shared.
She watched her old friend recount in what kind of state Sara was, and she heard the hitch in his voice when he stated that she had been in the dessert for an entire day. That hitch told her all she needed to know, this man was loved the woman they were desperately trying to find, deeply and with his whole heart. Catherine knew she had to say something, but was stumped, when she wasn't completely sure what she should say.
She knew Sara a little bit, but not much, like Grissom Sara was a private person. Catherine wasn't even sure whether or not Sara had a family who needed to be told what was happening to their daughter, sister, niece or granddaughter. Catherine knew Sara was a hard worker, she wanted justice to be done. She had been there when Catherine needed her, she had done several tough cases, she didn't shy away from the job at hand, even when it was doing an internal investigation. Sara wanted to find the truth. Sara had survived a few things already, she had been close to getting her throat slashed by a lunatic. She had been in a explosion, and had seen her doppelganger lying dead on a slab.
Catherine seemed to have two choices: She is a fighter or she is a survivor. For some reason Catherine choose to say: "She is a survivor." Catherine hoped that Grissom wouldn't ask her, why she thought that, because she wasn't sure what she would say. She didn't really have arguments to support her statement.
But Grissom looked at her and nodded. Catherine knew that Grissom had the arguments to support her statement. There was something about Sara that he knew and the others on the team not. It didn't surprise Catherine, Grissom loved Sara and had a relationship with her. The hitch in his voice had told the story, the story of the love Grissom and Sara shared.