Hi, yes it might be a good idea to mention it in a light hearted way. I sometimes drop it in to conversation if I just had a bad stammer. Just make sure you don't mention it in a negative way, 'ok I have a really bad stammer so you may not be able to understand me'. It's better to say something like 'just a little warning that I have a slight stammer' or something like that. The important thing to remember is that you are not being graded on your fluency. In fact if you can stammer and still remain confident, positive and generally optimistic it will show great character in an interview. Also take deep breaths when the interviewer is speaking to calm yourself (that's a tip for anybody) and speak slowly and clearly. Hopefully this helps and good luck! Keep us informed! Edit: just seem your update...oh well