Minutes of the May 5 meeting, released on Tuesday, revealed the reasons why that one board member voted to keep the cash rate at 4.1 per cent as the other eight members voted for a third straight hike.
Despite uncertainty caused by the Iran war, the majority agreed the risk the conflict would cause inflation to be higher for longer was more important than the downside threat it posed to economic growth and employment.
"Given this outlook, these members determined that the risks to achieving the board's inflation objective had risen and judged that they were not confident that, at 4.1 per cent, the cash rate would be sufficient to mitigate these risks," the minutes said.
But the unnamed monetary dove placed greater importance on the threat to the RBA's employment mandate.
They argued the economy was not running as hot before the Iran war as bank staff thought, inflation could return back to target quickly enough without the need for any more rate rises and inflation expectations were still anchored.
Speaking at a Bloomberg forum in Sydney, RBA chief economist Sarah Hunter was more concerned about inflation expectations.
"If businesses and households expect high future inflation, this can become a self-fulfilling prophecy as these expectations get baked into contracts for goods, services and wages," she said.
"It becomes harder for central banks to bring inflation back to this target as it must bring expectations back down and restore the balance between supply and demand.
"Doing so may require a more substantial slowing of economic activity, as we saw during the early 1990s recession."
The RBA has forecast businesses will pass on higher costs to consumers and noted some construction firms are reviewing prices for new contracts.
As a result, it has revised up its forecasts for headline and underlying inflation, before falling back to the RBA's 2.5 per cent target by mid-2028.
Though money markets were pricing in at least one more rate rise by November, they rated the chance of a June hike at less than one-fifth.
Dr Hunter acknowledged it was a challenging time for Australian households but getting inflation down would benefit everyone in the long run.
The economist spoke after Treasurer Jim Chalmers took to the stage to defend his government's budget.
Released a week ago, the budget has attracted blowback from the big end of town over changes to investor tax breaks and the use of trusts to minimise tax.
But Dr Chalmers insisted it would more accurately compensate investors for inflation, reduce "distortions" that would be bad for the economy and ultimately help in the fight against inflation.
"What we've deliberately done here is recognise that when you make important economic reform in this country, you're always going to get a hard time politically," he told the forum.
"But what matters more to us than the political turbulence from day-to-day or one opinion poll to the next, is to make sure that we get some of these longer term settings right in our economy."
The RBA is still digesting the budget and Dr Hunter said it would be factored into the bank's next set of forecasts.
Consumer sentiment bounced back slightly following the budget and lower fuel prices, according to surveys released by ANZ-Roy Morgan and Westpac-Melbourne Institute.
Expectations for inflation two years ahead eased from 6.4 per cent to six per cent in the ANZ-Roy Morgan index.
