Billionaire Warren Buffett said Thursday that economic growth has lost some steam recently.

"It does look like the pace of increase in the economy has slowed down," the chairman and CEO of Berkshire Hathaway told CNBC's Becky Quick at The Gatehouse's Hands Up for Success luncheon in Grapevine, Texas. "I'd call it somewhere close to noticeably, but I wouldn't go beyond that."

Buffett noted that a slowdown in BNSF, the railroad company owned by Berkshire, is flashing a signal of slower growth, but added that some of the data may be distorted by seasonal factors, such as the weather.

His comments came amid increasing concern that U.S. economic growth could be stalling. This has added to volatility in the stock market and has pushed Treasury yields lower.

The benchmark 10-year yield hit its lowest level since Dec. 5, 2017, overnight. Recently, the spread between the 10-year yield and its 3-month counterpart turned negative, causing a so-called yield-curve inversion. Inversions are seen by investors as a signal that a recession may be coming.

Still, Buffett said he is not concerned.

"But it does look like it's slowing down. I don't mean it's reversing course, but it does seem from all of the businesses, especially the railroad statistics" that the economy may be growing at a slower pace, Buffett said. "That doesn't change anything we do. If there was a flashing red light, if there was a blaring red light, we would keep investing the same way we do."

He also repeated his mantra of the United States being the best place to invest money. "You really want to bet on America," Buffett said. "God has blessed America."

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