Those are not fat wrinkles, they are the normal curve/wrinkle from bending. You can see how the edge of the wrinkles concave a bit?
A fat snake wrinkle looks like a stuffed sausage and the wrinkles are puffed...
here's a severely overweight boa to show what I mean (not my photo) http://www.animalsathome.ca/wp-conte...6562020926.jpg