His actions have malice in them. He knew what he was doing, and tried to hide it. Then he said he did it on purpose.
I wouldn't take it lightly. It seems to me to be a signal to watch since it was clearly directly against you and intended to cause you harm. It may be that, as his inhibitions become less and less due to the alcohol, that his less and less able to control his anger against you.
ShootingStar1