The caution expressed in this week's minutes of the Federal Reserve's May meeting may have been warranted as inflation has been undershooting forecasts for several months.
James Bullard, president of St Louis Federal Reserve, and one of the Fed's rate-setting open market committee, said the current trend for consumer prices was "worrisome".
Current levels of inflation were "noticeably" lower than they would be if the Fed had put more effort into maintaining its 2% target rate, Bullard said.
The central banker made comparisons with Japan's economy, which suffered two decades of low inflation, saying: "This is not as severe as the 1990s Japanese experience, but it is worrisome."
While the buoyant labour market and record high financial markets have distracted from low inflation and signs of slowing growth, the Fed has continued its rate-hike cycle, raising once last year and then in March to 0.75%-1%.
Yet most measures of inflation or inflationary expectations have indicated little pressure on prices. Indeed, the dollar has been on a downward momentum since the start of the year, while bond yields have dipped.
Core consumer price inflation in the US slipped to 2% in April, from 2.2% in March, while the Fed's preferred measure of inflation, the personal consumption expenditure price index dipped to 1.8% in April.