The recall affects about 6,000 vehicles that have been sold since the SUV went on sale in late December. Consumer Reports issued a "Don't Buy" warning last week on the 2010 GX 460, saying it was susceptible to rolling over.
The official spoke on condition of anonymity because no formal announcement has been made.
Toyota responded by halting sales of new GX 460s and conducting tests on all of its SUVs.
The automaker also agreed to pay a record $16.4 million fine on Monday for failing to properly report a safety problem with defective gas pedals.