A source told ABC7 News the patron was a man. He was passing through and stopped for dinner at Sauced. He also didn't live in this county.
RELATED: Possible measles exposure across Santa Clara County has parents on edge
One of the restaurant's regular customer, Michael Diaz, said, "We walked right by here-- what if the person came out and walked right by me at the stop light. I don't know, just saying."
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According to Public Health physicians, measles is an airborne virus and can be spread just by talking.
Dr. Nicholas Moss listed the ones who should be worried.
"Pregnant women, families with infants under 12 months at the restaurant, people with compromised immune systems."
The virus could have also lingered in the air for an hour after the person left Sauced.
RELATED: CDC monitoring 6 measles outbreaks across US as number of cases nears 2018 record
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Sauced, meantime, issued a statement, saying quote, "we have contacted all of our staff and there is currently no risk in our restaurant."
Some customers are shaking their heads.
Marino Giammarco said, "It's a little concerning-- nowadays people don't want to get vaccinated and we have the technology and resources to prevent stuff from spreading."