The warp is probably "Washout" When you build the other wing panel, it should also warp with the wingtip up at the trailing edge the same amount.

Washout is a purposeful warp which reduces the angle of attack out near the wingtips, helpng to prevent "tip-stall." Tip-stall makes a plane fall off on one side and spin, which is very bad when flying low and slow, such as when learning to take-off or land.

The warp does reduce aerobatic capability, making a tight spin difficult, and imparing some other maneuvers which depend on stallng a wingtip to get the proper snapy response. However, it makes the plane more stable, and easier for beginning flyers.

LT-40, I haven't read the instructions.

GP's PT-40 and PT-60 have significant washout, and are quite similar aircraft.

If the way the instructions say to build the wing created washout.... I'll bet its intentional even if not clearly explained.

Build the second wing. If they match it will fly just fine. If they don't then you gotta figure out which one needs correcting.

I've built over 30 Sig kits... (probly over 50... lost count years ago.) never had one come up with washout that wasn't intentional.

AND whether washout was engineered into the original plan or not, there's no desirable trainer characteristic that will be negated by adding it. The only thing lost is a little bit of lift and any ability the plane might have had to snap roll... the lift of the LT-40 is way more than sufficient to sustain a little reduction and there is no benefit to designing trainers to snap at the price of possibly inviting low speed tip stalls.

Some good things you get without asking for them. If you don't complain about the fuel injected engine in your car, and you don't complain about the flitration they run your drinking water through, why complain about washout in a trainer wing?