hickory sometimes does this, ive had a stave twist 45 degrees from center, as well as curving about 3 inches from the back. it wont hurt anything, as a matter of fact it will probably tiller out when you start building with it so i suggest you search for a caul design and heat some reflex into it anyway. the reflex will help offset the set or string follow that most bows gain during tillering. you could even leave the reflex stiff in the last bit of the tips and have a static recurve.