may be i am more curious ,so when this no-center point ,no-watcher ,or no-ego stuff become a real experience (word experience is a problem) .Like there is no I behind the experience sprout ?
So, for me, what you're describing sounds like its coming from the fresh, vivant, unaffective aspect of Equanimity --- getting closer to a suffusive or 'pure' state of EQ (whereas the "smug" and tense side of EQ is when a person starts to naturally cling to equanimity, reducing equanimity to its bear minimum little state that sits very, very close to the dukkha nanas, but is clinging to stay out of them directly). We could call these high and low equanimity, too; that's one convention. Low equanimity is very close to dukkha nanas (but can feel awesome the first few times it occurs after intense 'dark night'); high eq has a scopeless range of experience arising from more of what you're describing.
A high equanimity, which inherently seems to come up not-from-me and as not-me because it is purely equanimous, is a launching point for lots of not-me/centerless/vast kinds of perception of experience (which experience one recalls with kinds of hindsight view). It is from the mental state of high EQ that a person knows intuitively ego and conceit will someday have to be dispelled because the great meditation experiences (and much practicality) come from this pure (singular, undiluted) equanimous-intimately-engaged/immersed/merged mental state, which -- like you say, has no center, no ego, no relevance to an experience of "I behind the experience sprout" (fun word choice, Rony).
So I think you're describing an experience related to a higher equanimity mental state, maybe a moment of pure equanimity. In equanimity and near high equanimity immeasurable amounts of juicy, here's-why-we-learn-meditation-and-sati experience occurs. The more pure equanimity occurs the more experiences occur and which experiences only occur when there is first that centerlessness, not-me. It's like concentration and attention are super-charged just because ego-center, me-ness", stood down/ dropped out of the way/ went dormant for a bit. This all can sound a little epic, but, again, there are some very simple, amazing, low-key folks out there who seem to be experiencing this state most of the time.
Also, in a middling equanimity (not suffusive, yes diluted) experience a person can experience two rapidly toggling sources of experience: one which is sort of that scopeless completely neutral-intimate-engaging-merged-not-separate awareness and another source that is faint, small and me-like periodically rippling a personal awareness into the scopeless, massive equanimity no-center/no-watcher/yes-isness experience.
But these are just my words. The after-joy of equanimity experience is that the experience itself is a massive tutor for everyone who trains and experiences it in their own practice. It is vast and practical, insightful. Maybe you will share other eq experience as they arise.