The teachers issued a prompt reminder they wanted a pay rise and that lovely pile of loot in the $5.5 billion surplus would cover it nicely.
Green Party co-leader James Shaw wanted it spent on infrastructure.
In a bid to ward off raids on the kitty, Robertson swiftly set about issuing pre-emptive warnings that the surplus was more an Airbnb guest than a long-term tenant.
He pointed to the big-ticket items ahead, such as the ominous sucking noise from Shane Jones and his Billion Dollar Fund.
He also warned a chunk of it would be weather dependent. It would be the "rainy day" reserve.
Rainy days are relative. For Robertson it amounted to a stash for something like a future economic shock, or a natural disaster.
For Prime Minister Jacinda Ardern, a rainy day fund can be swiftly transformed into an election campaign fund should that rainy day not come in the interim.
For the National Party, news of the surplus and lower-than-expected debt levels themselves constituted a rainy day.
It had spent months dooming and glooming about an economic slowdown wrapping its tentacles around New Zealand and the wastrel Government frittering away the economic grounding left by National.
The books still reflect National's management - but certainly suggest Labour is not doing such a bad job at looking after things after all.
It is all rather inconvenient for National's leader Simon Bridges, who wants the economy to go a bit tits-up so he can start with the "told you so" routine.
In a bid to hurry that along, Bridges too set about coming up with ways to get rid of that surplus.
Reverse the petrol tax hikes and Auckland's fuel taxes, he suggested, and use the surplus to fund shiny rail projects in Auckland.
Of course, he wants no such thing to happen because as long as there are regional petrol taxes in Auckland and looming for the rest of the country after 2020, Bridges has a viable "cost of living" campaign to run on.
Bridges' goal is to try to make sure the Government cops the blame for that, whereas Ardern's goal is to shift that blame onto petrol companies themselves.
It has not helped the Government that the surplus coincided with sky-high petrol prices.
The surplus was largely built from higher-than-expected tax intake. That does not help when it comes to justifying the need for extra taxes.
If it does hang around, nor will it help if Labour's Tax Working Group comes back with proposals for new or higher taxes for Labour to consider as policy in the future.
Meanwhile, as all this goes on a former Finance Minister waits.
Steven Joyce appeared to have taken Rachel Hunter's hair as the life guide for his infamous fiscal hole.
Those who watched television in the 1980s will recall those shampoo ads featuring Hunter's locks and the catchphrase "It won't happen overnight, but it will happen."
So it is apparently for Joyce's fiscal hole.
The opening of the books this week revealed a hearty $5.5 billion surplus with little sign of the $11.8b hole Joyce claimed of Labour's pre-election plan, or indeed of any hole at all.
This did not escape the notice of Herald cartoonist Rod Emerson, who produced a riff on grafitti artist Banksy's self-shredding artwork by replacing the Girl with Balloon with Joyce and his fiscal hole, shredded.
Joyce was not giving up that easily. He retorted: "V cute Rod but probably a tad early ... This surplus is largely from our last budget - Give it two or three years and get back to me."
Pink Floyd did have some handy advice for Robertson on that matter: "Grab that cash with both hands and make a stash."
