Yesterday I tripped on a tiny clump of asphalt on an otherwise pristine stretch of road. Skinned my right knee and elbow, and bruised the pad of my left hand. Ran another 6+ miles with no pain except stinging from the scratches. I'm taking a precautionary day off, but I'm grateful that all I got was some road rash.
As to why I tripped? I suspect that I either looked away courtesy of road hypnosis, or I was distracted thinking about the next stop to switch music.