[Brian Duff]

I take you to mean that the sail cloth along the luff is doubled over in the luff groove, a pleat as it were ?

This should be able to be pulled back down with your body weight, or perhaps just having the sail out and pulling hard aft in this area will remove the 'pleat'. This happens often when hoisting a sail, and comes out easily, with perhaps 50lbs of force.

Use force( or a knife, then call your sailmaker ....)

but it will probably come out without damaging material.