Pop star Beyoncé opted to use a "pre-recording" of her rendition of the National Anthem during inaugural ceremonies in Washington Monday, a spokeswoman for the U.S. Marine Band tells CNN. "We don't know why the decision was made," U.S. Marine Band spokeswoman Kristen DuBois said. "She did not actually sing," DuBois added, noting Beyoncé lip-synched her own voice. DuBois said Beyoncé "pre-recorded" the song the evening before Inauguration Day, after rehearsing with the U.S. Marine Band. According to the band's spokeswoman, such pre-recordings are "not unusual." Recording musical performances prior to inauguration ceremonies are a necessity in case something should…