I've done the whole "why is my arm vibrating thing" before, except in my case I was trying to get the end of a light fitting off, and both the hot and cold prongs were in my hand. Got a nice couple of blisters where they touched the skin.

My guess would be not enough of the main current was passing across your heart to kill you? I didn't think mains electricity was necessary powerful enough to kill people in most scenarios, just that it is powerful enough to do it in an unlucky few. I'd also imagine the floor wasn't really conducting to earth.