I guess it is hard to say if he intended to do it or not. I would think that if he did, that he regrets doing it and would take it back if he could.
From a player's perspective, I know that sometimes the puck leaves the stick in a way that you didn't intend. Whether it be the angle/movement of the stick, or what, but sometimes it just doesn't go where you want it to. Like when you shoot the puck over the boards while playing outdoor hockey (crap, now I have to go find it in the snow! ). Even players in the collegiate/pro ranks do it, watching some players missing the net wide on a shot, or better yet, sending it sailing over the net.
I'm not trying to say that Lammy didn't intend to do it, because maybe he did, maybe he didn't. But I also think that it could have just been a puck that got away from him while he was trying to bank it off the glass. Only one person knows for sure, and that person is not any of us....or Slap Shot.