Late response but just found this sub: I stutter when I am tired. Usually I wax lyrical without a care in the world but when I am very tired (and that's very rare) and I have to concentrate, I stutter. It has made for a few enlightening presentations for work at the end of a long week - moreso in the Q+A because then I have to concentrate on what the other person is asking me. I usually explain myself though. This has been for all my life and as I say it is so rare that I am both super pooped and have to concentrate that it rarely comes up - could that be what you have - just really tired?