I know what you mean. I have had many higher states of complete freedom and peace like that...
We may be well speaking of the same state, or not; I have no way to tell. But what I am referring to, and what non-duality pointers refer to, is not a state that can ever be placed in a sentence like the one you have uttered as if that was a truthful description of the fact.
“I have had a Natural State” is not a possibility although it may appear so so convincingly. The Natural State cannot be had. Only the ego can claim that it had a state. In fact, the ego never has anything at all. Ego is a concept. A concept does not do, own or live anything.
Assuming you had a genuine insight into the Natural State, and not merely a higher mental kick, what you are describing is this:
Ego is active. Then the ego goes into abeyance. Because the ego is absent the ever-present Natural State becomes apparent. Then ego leaves abeyance and the belief that we are ego is re-instated as before. And ego claims: I had that state.
That is the closest that the intellect can come to describing what happened in actuality. Anything that is thought or said about the Natural State that begins with “I had” is imagination.
So, it is recommended to turn our skepticism and doubt towards the “I had…” statement and specifically “I”, and inquire within.
This is not rhetorical. And it cannot be understood conceptually. It requires looking closely and attentively at what is present. That is why the tool is called “self-inquiry”.
All study, all preparation, all practices, all “isms”, converge onto this action. That is: paying attention to what is There. What we had, or believe we had or believe we will have one day is of no importance whatsoever.