Not sounding out a word correctly

(Chapter 16 The Many Problems with Words in my book)

I read the word “fast” as “faste”. In other words, I said the fast with a long a sound instead of a short a sound. That was very weird that I did that. A few seconds later I read it correctly. I know that this has happened to me before and I am pretty sure that this wasn't a problem before the symptoms of mild cognitive impairment invaded my life.