Robert
That certainly seems to separate the issues of moisture and epoxy shrinkage, since the foam should not be affected by moisture.

I believe what happened on the 1/2 laminated wood was that the wood picked up significant moisture and warped.
The moisture would have progressed thru the wood on a time basis heading to equal moisture pickup thruout the thickness after days or weeks.
When I dried it out quickly, some of the moisture deeper in the wood was retained while the outside layer dried out.
The outside layer has the most effect on bending, so it came into straightness in spite of higher moisture inside the wood.
I laminated it, trapping moisture in the center, with dry on the surface next to the new glass.

Over the next few days the moisture in the wood migrated back into the outer surface. Since this has the most effect on the overall panel, the panel again warped but less, since now there is the stiffness of both sides laminated to resist warpage.

Thanks for the information.
The boat is finished, unfortunately the warp is within 1' of the stern - not in reach of a access cover ( which may not be installed ever).
Grin and bear it is what I am left with - or rather the friend who owns the boat. So we decided to call it a "feature".
As in - look at this cleaver shape I built into this boat just for visual interest - I intended to do this!

There was one lesson learned (to me): dont ever build a kayak with flat surfaces - just a little curvature would have made the issue unrecognizable Most of the time.