Looking out for someone's safety always has to be the right call. If nothing was said, the behavior could continue, or get worse. At least maybe there will be pause on the student's part when the next opportunity to get fried arises.
I'm a manager at a trucking company. Just a few days ago, a driver supervisor came to me for advice. She suspected one of her drivers was drinking before work. The supervisor was worried about affecting this driver's livelihood and was unsure how to proceed. She worried about embarassing the driver. I'm sure you are screaming "of course she should take action to get the driver off the road!! People's lives are at risk!". That's exactly what was done, but my point is that so many of us seem to worry about hurting someone's feelings we don't see what good could come from the discomfort. You know, forest through the trees, and all that.
Obviously, the damages a drunk driver of a driver of a 50 thousand pound rig could cause are greater than a student "tripping" in class, but no matter... the right thing is the right thing is the right thing.