When you set her on the bed, and paid her no mind, she probably felt a lot more vulnerable with so much open space around, as opposed to being held. And I find when I don't pay attention to my snakes while I have them out, that's when they surprise you. Some smell, vibration, movement etc. can set them on the defense. Always be aware of them. Also, if your handling her with fear now because of what happened, she will pick up on that and it will make her frightened if your not as confident. As Jimi said, double check your set up and make sure temps, humidity is good. And give her a little extra privacy, I cover my glass tanks with a scarf to make it dark so the snake feels more secure. Hope this helps.