Sure, mindset is a factor. But stuttering is much more complex than that. That's why it's hard to figure out, after all. We simply don't know enough about it yet. Stutter doesn't go away as a result of forgetting. However, when we sometimes speak without stutter, sure, we might be able to forget that it's a thing. So, it's the reverse, really. At any rate, stutter variance is one of those things that are really hard to get used to, exactly because the contrasts can be so huge.