The incident happened less than a week after Republican candidate Meg Whitman used a video clip of Clinton in a TV ad attacking Brown.
Whitman put a short clip of a 1992 debate between then-presidential candidate Clinton and then-presidential candidate Brown.
"He raised taxes as governor of California," Clinton says in the ad. "He had a surplus when he took office and a deficit when he left."
That apparently didn't sit very well with current-candidate Brown who told a crowd in Los Angeles this weekend that Clinton doesn't always tell the truth. Brown then made a comment that brought back a infamous phrase from the Monica Lewinsky scandal.
"I did not have taxes with this state," Brown told the crowd.
Brown apologized for that remark Monday. "It was wrong for me to joke about an incident from many years ago, and I'm sorry," Brown said.
Brown told reporters he personally called Clinton's office to apologize. He said he didn't get the former president, but instead spoke to one of his aides.
Time magazine posted a rough clip of the event, but did not identify who shot the video.
So far, Clinton has stayed quiet on the issue. He has not endorsed Brown as of yet. The testy relationship between Brown and Clinton is still apparently very much alive 18 years later.
Clinton came out surprisingly early to support San Francisco Mayor Gavin Newsom's gubernatorial bid before it flamed out.