Warren Buffett waves off Fitch's cut to America's credit rating - and says he's buying Treasuries as normal

• Warren Buffett isn't stressing about Fitch's cut to America's credit rating this week.
• Berkshire Hathaway continues to buy $10 billion of US Treasuries every Monday, he told CNBC.
• Buffett said the US dollar's status as the world's reserve currency remains intact.

Warren Buffett isn't stressing about Fitch's shock downgrade this week of the US credit rating from AAA to AA.

"There are some things people shouldn't worry about," he told CNBC's Becky Quick. "This is one."