On every stripper I have done, the deck breaks loose from the forms during the sanding process. Most of the time I have a 1/4" as you do.

I press it down tight before I glass it. I know from experience that you can pull the deck and hull together using fiberglass packing tape with usually no problem.

The deck an hull never fit together perfectly, especially after you sand and glass the insides. Epoxy shrinkage forces and forces of the wood will always distort it a bit. When you're not working on it, keep it strapped to a few of the forms. That little space you describe is nothing to worry about.