I have had a very bad experience with rats in the past. When I was about 8, my grandma got me a pet rat which seemed pretty nice at first. The first time I reached into the cage, he bit my finger about 3 times! When I got him home, he bit me so hard I could see the bone in my finger! So I don't have that much sympathy for rats. Although I still would not want to feed live rats to my snakes.
MOST are not like that at all!
And there are reasons I can think of why the one you got did bite. They can bite out of fear, or too many hormones, or because they are such social creatures they can go psychotic if forced to live alone.
So far in my lifetime I have owned 18 pet rats, and only one was a biter. And he wasn't a bad boy really. After I understood his issues we got along just splendidly...
:-offtopic
I should not say this, but everytime I see your nic all I can think of is that song.....(b-b-b-bird bird bird, the bird is the word.....)