Now that he wasn't too busy being a complete and utter idiot, all flabbergasted and shocked, Kol could actually really appreciate the sentiment and what it meant for the demon to own up to it. All of this was just as new to Crowley as it was to Kol and there was a sort of commiserating sort of feeling to know that, at least.
But that didn't mean he had any idea what to say. How did you respond to something like that? The entire situation was screwed up and there was a part of him that wondered how much doubt and skepticism was running through Crowley's mind. Because from a personal standpoint, there was a lot left inside Kol's own mind. He would always be a suspicious sort, it was the nature of living the life he had, but that didn't mean anything he felt was any less for it, did it?
"Well...thanks." he mumbled, albeit a bit awkwardly, but he meant it. He really did. Kol wasn't sure how to explain it exactly, but it meant...something. It mattered that he'd even bothered to check in.