The 35th Annual GMA Music Awards (the show had a name change in 2004-05) were held on April 28, 2004 recognizing accomplishments of musicians for the year 2003. The show was held at the Municipal Auditorium in Nashville, Tennessee, and was hosted by Deion Sanders and Yolanda Adams.
Fifteen years ago, the GMA Music Awards gave recognition to accomplished musicians for the thirty-fifth year.
2004 was the date of the 35th Annual GMA Awards and 2004 was fifteen years ago, so the statement is correct. The system might have tripped on the convoluted way the statement was written.