You did well to notice it on the edge of a trail. Looks pretty lethargic, or at least accustomed to seeing a few people pass by. Our snakes over here just would not lie around like that. A whole lot more active.
Super cool! I've found my share of Timber rattlesnakes over the years. Some on purpose, some by accident. I have yet to come across one of these guys. I hear they are rather moody when compared to rattlesnakes.