I've come to understand the "friend zone" as a place where a person puts himself by being too spineless to either ask out the person in question and make their feelings clear, or resolve them internally on their own time and make peace with not pursuing them and keeping them as a friend. It's a painful cognitive dissonance that is brought entirely upon oneself. The proper way out is growth, but many just rage at it and refuse to change themselves.
I relate to this. But I think generally the term is used to mean when you ask the person to take the relationship to something more than friends, but they'd rather stay friends. We should come up for a name for what you say, the self-imposed friend zone?
I would say it's still the same spot, because at that point the feelings have been resolved on one end, and it's your responsibility to deal with yours. If you're okay with staying friends, that's fine. If the rejection is too painful and you need some space, just let them know in a respectful way and take time to handle your emotions.