It sounds to me like these episodes are involuntary and therefore probably not normal. Like maybe he is hallucinating. Luckily he is aware that what he is experiencing is not "real". I would probably ask doctor about this, maybe try to get a referal to a neuropsychologist or psychiatrist. Esp. since it is now bothering him.
DD has ADHD and her EF ability is impaired enough that she does not come up with stories of any kind. But I can't say that is the case for all people with ADHD. However, it just doesn't sound like it's related. People with ADHD can be distracted by their own thoughts, or distracted by what is going on around them, but these bizarre sounding dialogues or stories don't sound typical of ADHD.
