"When a reporter asks a sarcastic question, you can see it in my face," she said. "I'm like, 'Really --- did you just ask that?' Because that's how the mayor is reacting in the tone of his voice. But I'm doing it on my face."

She told Colvin that she began signing as a child for her deaf mother and three siblings.

But Wednesday afternoon, Callis was gone, replaced by another woman whom Bloomberg introduced at his news conference as Pat Mitchell. She did not return for Thursday's briefing.

"Lydia Callis has been replaced! Feel bad for this woman signing now. Like trying to freestyle after JayZ has just performed," tweeted @janvijhaveri.

"Bloomberg's new signer does her job fine, but she doesn't have panache of Lydia Callis, who signed with a New York accent. Bring her back!" posted @MahaRafiAtal.

"Awww what happened? Bloomberg didn't like all the shine Lydia Callis was getting? Or did they just finally give her a break?" @DeePhunk wrote.

The mayor's office, obviously with bigger matters to address, did not respond to CNN calls or e-mails about Callis and her replacement.

Callis has remained mostly silent, not jumping into the New York media circus -- yet.

Silence is a job requirement, according to Kim Kurz, who chairs the American Sign Language & Interpreting Education department at the National Technical Institute for the Deaf.

Callis earned a degree in American Sign Language from that school, which is part of the Rochester Institute of Technology, before moving to New York City last year, a school spokesman said.

"We are honored to see Lydia's skills recognized in this situation and send her our best wishes for continued success in her profession," Gerard Buckley, the school's president, said in an e-mail to CNN.