Len, you say you are ready for glassing. Does this mean you have already lined the flap well? Has this warped as well?
One thing you could try is glass the center section with 2oz cloth out to the end of the flap or near to as mine ended up and make sure you glass the rear 'flap lip'. Lay the wing flat, cover your fresh glass with some food wrap and put some weight on it to flatten it out and let dry. 3/16th doesnt sound like a lot but you will notice and know it is there.
Let us know how you go.

Cheers,

Brad