Thank you all for your advice. I'll get rid of the cedar.

Maybe its inactivity nothing to worry about; I just freaked out because it seemed like such a sudden and drastic change in behavior. I guess I'm inclined to worry too much because years ago I kept several ribbon snakes (sequentially) and they all stopped eating and died within months. I never figured out what I was doing wrong (the folks at the pet store couldn't explain it). So I'm kind of paranoid that the same thing will happen to this snake.