Remus might have gotten upset if Severus snapped at him. Because really, that kiss still left his knees weak.

"No, no. The first few times it'll only happen when you're experiencing something emotional - like a Patronus. It still needs a lot of concentration to happen. And considering you were concentrating on it before the-- we... it. Well, it happened." Remus tried to say, getting entirely too flustered at the end. His cheeks reddened again.