I think I've experienced this a few times, even though I'm not dyslexic. This happened when I haven't slept for long time and reading something at 4 am gave me that "thoughts out of focus" feeling, when the words are right in front of me, I know I can read them, but experiencing a funny difficulty assembling the letters together. This also happened a couple times on the half-asleep state when I've almost woken up, but still seeing the dream and for a few seconds I had this strange "out of focus" state when focusing attention on words or speech is difficult.