Can you post a pic, perhaps one of us will recognize what you're seeing if we see it too...
As the wrapper dries down, it usually tightens up...
Eggs Ackley
What variety of wrapper?
How damp is it?
What shape?
I find if I'm wrapping a figurado, damp wrapper of a stretchy variety will shrink down nice and tight around the compound shape. But if I'm wrapping a parejo, you can go with far less damp. But even if you do dampen a parejo wrapper, it's not gonna wrinkle.
I spose that if your wrap is damp and yet you have wrinkles after, then, either you are not stretching it tight enough between the thumb and forefinger of the hand you use to hold the wrapper to the board, or else your other hand does not constantly hold the stick tight to the board.