@nprofile1q... Nice photo!
Just curious: were you third in line on the trail?
Preparing for the first field trip of my first geology course, Prof. Spence told us, "We're going out in the field after the snakes are in bed but before the snow flies. Nevertheless, be careful! The first guy on the trail wakes the snake up, the second guy pisses him off, and the third guy gets whacked. " Oversimplified, but with an element of truth.
Any indication what might have annoyed or frightened this snake?