Help! My cornsnake scared me!?

They are supposed to be a good 1st snake. He has been fine until today, when I went to take him out of his tank where he feeds, he jumped at me and shook his tail just like a rattlesnake! It took all I had to pick him up to put him in his enclosed tank and he kept doing the rattler thing and folding up like an attack. Now Im scared of him. :( Is it normal for him to shake his tale, it was vibrating the tank! :0