This week at $dayjob I was editing some text in my editor (emacs) to be copied into $mailclient as text of a message. I typed away, leaving out some detail at first. Then I returned to that spot to fill in the details. So far, so good.
After that I reread the message text. And the last paragraph of that text looked completely /new/ to me, as if I had never seen it before. But of course I did type that text in myself just a few moments earlier.
This caught my attention as quite /bizarre/ --- possibly for the first time to notice, that my brain had somehow failed. Weird! Surprising! And scary, too!