According to an episode of SnakeBytes TV on youtube (Brian is awesome), you can use a little capful of Listerine. He shows the difference between a defensive strike and feeding response bite (what you described), and explains the best way to get them to let go. I would consider looking that up. It was a good video.
Sometimes the water thing works, I think it just depends on the snake. But according to Brian, Listerine works every time. lol.