The decision to put the WWE World Heavyweight Title on Seth Rollins at WrestleMania 31 was not a last minute decision but very few people were aware that it was happening.
The Wrestling Observer Newsletter reports that Reigns was originally planned to win the title and Rollins found out that he would be winning it late in the show. He was also informed that after winning, he would have to take the flight to New York City for The Today Show and the back to California for RAW.
Rollins reportedly was informed that he was winning the title by a WWE producer right at the start of the angle between The Rock and Ronda Rousey. Rollins, Reigns, Brock Lesnar and Paul Heyman then worked out the new finish with Michael “PS” Hayes. The rest of the match had already been mapped out by that time.