On the heels of a great job market report from the Labor Department, billionaire and investor Warren Buffett says he is also optimistic that the U.S. job market will continue to improve albeit slowly.

"The economy is improving, not at a rapid clip, but this country has done well since 2008 - certainly compared to the rest of the world," Buffett said to CNBC.

Buffett thinks it would be extraordinary if the Federal Reserve were to expand its bond-buying program beyond the current $85 billion a month level. The Fed said Wednesday that it would consider buying more if the economy needs help.

In a separate interview with the Fox Business Network on Friday, Buffett tried to reassure Berkshire shareholders that they shouldn't worry about his successor.

The 82-year-old billionaire said he isn't concerned about who will next lead four companies in which Berkshire invests nearly $50 billion, such as Coca-Cola, IBM, Wells Fargo and American Express.

"I don't know who's going to succeed the present CEOs there and in every case, each one of the four they have changed CEOs since we started buying the stock in certain cases more than once," Buffett said. "I never knew who they were going to be. I knew they'd pick good people."