Being an addicted bass fisherman, I've had more than my fair share of close encounters with cottonmouths. Like you, I'm lucky to have not been bit.
I believe the heat down here in the south makes 'em lazy.
Actually...Snakes can/do get overheated...so be kind to snakes, they are not Ba$%a*d liberals...they are one of nature misunderstood creatures.
We were vacationing for a week with some friends at their house on the lake in southern VA. My friend's wife was walking along the road not paying too much attention when she noticed something move onto the road about 10 yards ahead of her. It was a cottonmouth about 5 feet long. She stopped in her tracks and the snake stopped. She moved over to the right side of the road and the snake then moved across a little closer and stopped. She then moved back to the left side and the snake then reversed course also. She started to get scared because she felt the snake had his eyes set on her. She then moved back again and the snake followed coming closer to her but then stopped directly in the middle of the road.
Now, getting very nervous she was getting ready to start heading back to where she came from when she heard the roar of a big ol' 4x4 pick-up coming up from behind her. The truck slowed down and pulled up just beyond her and squashed the snake. The driver, a young 17 or 18 year-old local kid then backed up to her turning down the country music blaring from his stereo and said, "There, he shouldn't bother you anymore, can I give you a lift?"
She hopped in and he dropped her off at the house 1/2 mile down the road.