Rick Carlisle and Rajon Rondo exchanged some words last night in the Mavericks 99-92 win over the Raptors and after the game Carlisle said it was just a "difference of opinion." The exchanged happened after a Raptors basket as Rondo was taking the ball up the court. Carlisle was yelling "Hey!" to get his attention (for a play call, presumably) and eventually called time out when Rondo never responded. One Redditor claims to have been sitting near the bench and said the argument continued there as well, with Rondo yelling until an assistant coach had to calm him down.
This was with 8:10 left in the third quarter and Rondo never played another minute. According to ESPN, the two have been battling over playcalling duties and since he's the coach, Carlisle wins those battles. But since Rondo's the one with the ball, he doesn't really have to listen. And there's your difference of opinion.