Yeah, a majority draw is pretty rare in MMA, but it's what happened tonight. In a majority draw, two of the three judges agree there was no clear winner to the fight, while the third judge believes one fighter won. Bearing in mind that each judge's scorecard is different, and each judge gets a say (it's not the addition and subtraction of all the scorecards that determines by points,) the fight is called a draw on the basis that 2/3rds of the judging panel found no clear winner.
Majority draws in the UFC nowadays are pretty rare with the way the judges use the 10 point must system. In fact, I'm not sure I remember one at all, let alone in a main event since BJ Penn / Jon Fitch