So I sit down just now and check in, as you do every day or three...
And find myself logged out for the first time in years.
Log in.... incorrect password. Check Keychain Access, reenter it, no dice.
Reset... still no joy. Reset again, and this time it takes. Change it back. All good now.
But it did strike me as rather odd. Hopefully I'm all good for a decade or two before this happens again. ;)