I have the same, but the reason is different. If I block without forcing, then people hear nothing so for others it looks like that I'm not trying to speak while I"m in a block. So whenever I'm out of a block, I speak fluently for some time and in my experience people sometimes say that I'm faking stuttering because I"m not forcing or repeating.. but the reason is, they don't notice it when I'm blocking whereof they think I'm not speaking.