That happens when you push in one or more of the CA hinges too much when you glued them. What you don't want to do is push on the elevator after you have already glued one of more of the hinges. You MUST let the remaining hinges relax when you drop CA onto them. It's easy to make this mistake with a big long elevator like the Kadet Senior.

You'll probably be allright flying it as is, especially on something as tame as the Kadet, as long as you don't over power it. In time though, the engine vibration will likely snap the tight elevator hinge(s) around enough to cause it to fail. Even then, I doubt you'll loose control entirely since there are so many CA hinges on that elevator, and not all af them are going to fail all at once..

I would test fly it the way it is. If the "bowing" and snapping doesn't cause any unpleasant flight characteristics, just go ahead and fly it as is. Do check the hinges regularly for signs of failure. OR, you can find out which hinge is the tight one If it is one at either end of the elevator, cut it and install another CA hinge right next to it. If it is an interior one, you might be able to do the same, but it'll be tight to squeeze a CA hinge in.