It happens to me too. I started stuttering over four years ago at age 63 … yes, really. Neurologist said I might have had a small stroke. However, my stutter has almost completely disappeared … **almost** because when it comes back it’s with a vengeance, and when I think about it. Additionally I’m blocking more. My blocking and stuttering, fumbling for words and to express a thought is getting worse and gets to a point that I just stop trying to talk. I think that anything involving the brain can throw curves and not play by the rules.