The superstar wowed a crowd of more than 800,000 people as Obama was sworn in for a second term by performing a flawless rendition of the National Anthem, backed by the U.S. Marine Band.
She has received nothing but rave reviews for her performance, but now a representative for her backing band, Kristin DuBois, has confessed Beyonce was just mouthing the words to a pre-recorded studio version of the track.
She tells the New York Post, "All music is pre-recorded for the ceremony because there are so many eventualities and conditions that day. We performed, live, the band. But we received last-minute word that Beyonce was going to use the pre-recorded vocal track. Those were the instructions we were given."
It's still unclear why the Grammy winner chose not to sing live, like fellow performer Kelly Clarkson, but band director Colonel Michael J. Colburn reveals Beyonce only had one day to prepare for the gig since she has been busy rehearsing for America's Super Bowl half-time show next month (Feb13).
On Monday he told news website Buzzfeed, "As soon as we get information from the Presidential Inaugural Committee (about) who the guest artists are going to be, we make contact with them, find out how we can prepare arrangements that will really kind of flatter their voices - of course in the right key.
"We had Kelly in over the weekend (19-20Jan13) to rehearse and record. Beyonce, she's getting ready for the Super Bowl, so we didn't have a chance to do anything with her until last night (20Jan13)."