It is really nice asking this! If it comes up, I would bring it up how you did not notice his sutter on the first date. I am about to start dating and this is one of the things I am very self conscious about. I know many stutterers, including myself, who are overly critical and tough on themselves on stuttering. He was probably extremely tough on himself thinking he came close to stuttering. DO NOT FINISH HIS SENTENCES OR INTERRUPT HIM IN WAYS YOU WOULD NOT INTERRUPT OTHER PEOPLE! You know him better than we do, but I would just stay away from saying his stutter is cute. It is probably something he does not like about himself, so to reinforce that as part of his identity probably will not go well.