That's because their coach, Chuck Pagano, returned to the sideline after missing most of the season battling leukemia. A great story, which you can read and watch more about over here via our friends on The NFL Today.
[Recap: Colts beat Texans]
Or you can just enjoy this GIF, which is probably the best postgame celebration I've seen since good ol' Jim Zorn's hip-hip-hooray festivities. OK, it's much, much better than that.