Lazarus cants his head, considering Sonia's words.

"The gratitude really does go both ways. Knowing how busy Mr. Factor tends to get, you've always been a remarkably efficient liaison for him. I've never once felt like I had to wait long on a request to keep Shepherd's Haven running smoothly, and I feel that you're largely to thank for that."

It might be his way of trying to deflect envy; he thinks he's usually good about not flaunting his intelligence, but when he does, he tends to only realize it after the fact.