This:

…before being released from the bucket in which I transported the snake from a friend’s house.

One cannot age a rattlesnake by simply counting the rattles (they gain a rattle with each molt, but usually molt more than once per year). However, this one was a youngster, maybe two years old? My post from June 2013 has a look at their teeth and some better scale shots of a larger individual.

May your crawlway be strewn with sunflecks and chipmunks, young snake.