I've had a couple lately. Not that my playing is perfect, but I get into a zone where I'm totally relaxed, and time almost seems to slow. I know where I'm at and don't need to think about that, instead, I'm planning where I want to be next and how I'll get there.
I think an analogy might be driving. Like when you first start, it's a little overwhelming, all the things you need to be on top of: blinkers & brakes & clutches and not hitting anything lol. Then the mechanics of driving become second nature and you just start focusing on the road ahead.
It's like a little taste of what it must be like to be truly skilled. ....Someday.... :)
...so ever since then, I always hang on to the buckle.