Too much work kills your brain cells.

Happened to me before, too. And for some time I kept going to my own superuser.com post to have a list of special characters to bind actions to in Notepad++, because it shows the American characters for keys, even on a German keyboard.
And it has happened about 10 times so far that I wanted to comment something on an old YouTube video and found pretty much the same comment by me on it already, years old. Once I even found that comment and a reply by myself that this had happened, so I actually wanted to comment the same thing three times.

…and I just started reading a DevRant post and suddenly noticed the green ++ icon.

I have unashamedly self-answered questions on SO before for this very reason - I knew full well I'd end up doing just this.

@AlmondSauce I posted my Notepad++ question exactly for the purpose of answering it myself. SE wants to be a knowledge base, so I contributed my knowledge instead of just writing it down privately (probably in a place where I would have searched for it much longer than simply going to my SU account or googling the question).

@Fabian Absolutely. I've never had any flak from anyone on SO for self answering a question - it's very much encouraged.

I can confirm this has happened to me

This has happened to me as well. Amusing to find so many other people it's happened to as well xD