"Please, don't dwell on it. I have forgiven it, as I hope you can forgive me for doubting you."

For all the Cuthbert is usually calm and collected in social situations he's not entirely sure what to do with R right now, so he fidgets a bit. Surely the zombie won't mind if he leaves at that last statement?

"If not before, friend."

And then he hesitates, because that might be a bit much to say to R right now. But what's done is done and he can't really take it back without making it worse. So he gives R a short salute goodbye and heads out again, he will need to think things over more before he talks to R again.