Did you disclose your stutter at the start of the interview? Doing this usually helps the panel understand what's going on. I usually start off by saying something along the lines of "I'm sure you can tell, but I have a stutter. I've had it for my whole life, but I don't let it effect my work life in any way." By the sound of it though, they didn't seem to mind. That's a good thing! EVERYONE is nervous during interviews. You haven't been told no, so don't give up hope.