JAKE GYLLENHAAL...ASSHOLE?

O.K. So what is wrong with Jake Gyllenhaal?? I always thought he looked so cute and sweet, until now. While promoting his new movie "Jarhead" (terrible title!), Gyllenhaal told reporters about an incident where he went off script and punched out a co-star. The Scoop describes the incident as such:
In one scene from the movie about the 1991 Gulf War, Gyllenhaal’s character puts his rifle muzzle in another actor’s mouth.
“When I pulled it out, [I hit myself in the mouth and] I remember I looked down and saw that my tooth had come off,” Gyllenhaal told reporters while promoting the flick. “For some reason,” Gyllenhaal said, “I just got so angry that I had chipped my tooth ... and just started hitting him and we didn’t talk for a month after that.”
Director Sam Mendes said the actor just got lost in the moment. “It’s 115 degrees, you’re away from trees, cars, everything,” Mendes told the Calgary Sun. “You can’t hear anything because the wind’s blowing. You don’t have your clothes, your car, your girlfriend, anything. And I really think Jake forgot he was acting a lot of times.”
Huh??? What??? Am I reading this story wrong? Gyllenhaal hits himself in the mouth, chips his own tooth off but then beats the co-star because he is angry?? And then instead of apologizing, he doesn't talk to him for a month after? HUH?! And what up with Sam Mendes saying, "oh, he just got lost in the moment..." WHAT? This is OK? This kid was making a MOVIE about war, a far cry from the stress/trama of actually being in a real one. Please tell me, what am I missing here?
THE SCOOP