Felpro exhaust manifold gaskets have paper on one side, metal on the other. The paper side sticks real well to the head, and the header pull away cleanly from the metal side. I've used the same gaskets for several header on/off. To me, as long as the gasket is in good shape, not breaking apart, etc should be ok.
Many years ago my sister inlaw died from car exhaust inhalation so I know what your worried about. We all miss her. She was good person.
