Not a long enough heat Fred. Its not ruined either. Those are "stretch" cracks and can be filled with super glue and stay perfectly stable for a long time. Tip flipping forms should be at least 18-25" long so you can be sure the limb stays aligned as you bend it. Yoru close, dont quit now. Heat the twist back out and move along. Dont get discouraged about a tiny set back like this. Your bow is more than long enough to support the flipped tips.