I stuttered for about 60 years, until 8AM on Monday, June 7, 2021 when I suffered a stroke. I was in ICU for 2 weeks, and not entirely conscious during that time. A couple of weeks after my discharge from the hospital, I was visited by a physical therapist. When she left, my wife commented, "Do you realize that you were perfectly fluent the entire visit?". I've been pretty fluent since then. My interpretation of this nifty change of events is in line with your conjecture, namely that I simply forgot that I stuttered.