Aliciakeys bb
BlackBerry President and Chief Executive Officer Thorsten Heins (R) looks on as new BlackBerry Global Creative Director Alicia Keys speaks at the BlackBerry 10 launch event at Pier 36 in Manhattan on Jan. 30, 2013 in New York City. - 

In the digital age, celebrity endorsements can easily go awry. Or perhaps “a-Twitter,” in this case.

Yesterday, pop star Alicia Keys added some pizzazz to Blackberry’s launch of its new Blackberry 10 in New York. She told the audience she and Blackberry were now “exclusively dating.” But one of Keys’ 11 million-plus Twitter followers noticed she’d been posting just days earlier from an iPhone. Soon the media was calling her publicist to find out just how committed the singer was to Blackberry.

“The first thing I thought was, oh boy,” says Chryssa Zizos,  president and founder of Live Wire Media Relations. Zizos says managing celebrity endorsements was easier for companies in the “old days,” when you worried mainly about DUIs and extramarital affairs.

“Today celebrities have this instantaneous access to their fan base,” Zizos says. “And it’s that stream of consciousness that we worry about today because you can’t write that into a contract, what you will and will not communicate with your fan base.”

Companies can’t easily control what their celebrity endorsers say on sites like Twitter, and it’s possible for followers to see which gadgets they’re using to say it. Tim Calkins, who teaches marketing at Northwestern University’s Kellogg School of Management says social media technology makes celebrity messaging more transparent.

“Now everybody can check and verify what people are doing,” says Calkins. “So in this case, somebody says they’ll be the new spokesperson but then very quickly you find out that maybe that isn’t as robust an endorsement as you thought it was going to be.”

A spokesman for Ms. Keys emailed reporters this statement yesterday: “The Internet is buzzing with speculation as to the exact time Alicia Keys ‘broke up’ with her previous smartphone. After a transitional period, she’s officially an exclusive BlackBerry 10 user today.”

Oprah knows this sort of Twitter faux pas firsthand. In November, she tweeted her love for Microsoft’s new Surface tablet from her iPad. One blogger sniped: "Surface ads, now brought to you by iPad.”

Follow Sarah Gardner at @RadioGardner