Both Reaves and Maroon are known for the intimidating, physical side of their games. As such, it should come as no surprise that the players would try to intimidate each other before the game started. This took the form of both players skating right up to the center ice line, while the rest of the players took their normal warmups in the respective zones.
The two forwards were rather nonchalant about it, but it was obvious that the players were sending a warning to each other. This is just one of those traditions that exists within the culture of the NHL. Reaves made sure to completely cross the center ice line at least once, breaking one of the unwritten rules of the sport.