It prompted an immediate hunt for the one or two ministers in question.
The big one was quickly ruled out: Bill English confirmed he would stand on the list again.
Others also ruled out retiring.
In truth, the ministers who intend to retire probably do not even know it yet.
Key is yet to tell them.
The word "Heatleyed" has become a verb in National after Phil Heatley (and Kate Wilkinson) were unceremoniously "retired" before 2014 because Key was bored with them.
Even Key admitted they had done nothing wrong, he just needed gaps for shiny, new toys. They were dispensable.
He wasn't called the smiling assassin for nothing.
Ministers are terrified of being Heatleyed themselves and, with some exceptions, it is almost impossible to tell whether they will be.
It came completely out of the blue for Heatley and Wilkinson.
In the absence of ministers who volunteer themselves or self-immolate in their portfolios, Key will likely target those Jim Bolger reportedly called "tillers of soil".
Those are the workaday ministers like Wilkinson and Heatley who muddled along but did not exactly set the world alight.
A number of names have been speculated on - Craig Foss, Nicky Wagner, Louise Upston, Sam Lotu-Iiga for general ordinariness. Murray McCully is named every three years for reasons of longevity, but has said he will stay as long as the PM gives him foreign affairs.
Chris Finlayson is in the same book - his main desire is to stay until the Treaty settlements are done. That was supposed to be 2017 but Ngapuhi's recalcitrance may well preserve him from early retirement. Should he have actually hoped to leave, Finlayson has also made the mistake of making himself indispensable to the PM over the intelligence review.
Speaker David Carter has told Key he wishes to stand on the list again and continue as Speaker should National be re-elected.
That will close off the option of moving a minister such as Anne Tolley into the Speaker's role to open a gap on the ministerial benches.
Key's version of expired goods often does not coincide with the Opposition or the media's version.
If the Opposition's version prevailed, Housing Minister Nick Smith would be the first to "retire".
As it is, Labour leader Andrew Little's four calls for Smith to be sacked have probably saved him instead.
Key's skill is in managing to ensure his chosen weakest links go quietly rather than with a great head of steam - and stay quiet.
There is a fine balancing act between keeping hope alive for promising backbenchers and trying not to create tension among ministers.
It is dangerous territory, the reshuffle business.
It is why Key rarely undertakes radical reshuffles, even after elections. He takes the same incremental approach to Cabinet reform as National has to wider reforms.
That sees him use natural opportunities such as elections or voluntary departures to shake things up a bit where he can.
Nonetheless, Key's utterances this week prompted all sorts of unusual behaviour from ministers.
Jo Goodhew seemed a tad puzzled about whether she planned to retire or not.
She said such things would be revealed "in the fullness of time", then that she could not reveal her discussions with the Prime Minister and then that she was keen to continue in her current roles. She was right about one thing: "that will be up to the Prime Minister."
That saw even Police Minister Judith Collins referring to herself as a "mere minister".
That was after she was asked by the Police Association how many more police officers National intended to fund.
Collins observed such a thing was for the PM's personal attention rather that announcement by a "mere minister".
It pays to know your place when the Prime Minister is restocking the fridge, even when you are Judith Collins.
