"No." He'd literally already said he hadn't, he thought, but Nick got that this was a shock. He was going to be patient. Or try to be. "I smelled it on her."
Which meant that Diana didn't necessarily have to know herself yet. It meant they hadn't even had to exchange hellos for Nick to know. He just had to know what she normally smelled like and had to notice the difference. And if he did, it couldn't be that new. He wasn't known for his nose among the Pack.