By all means go to your nearest hobby shop and buy some new aileron or trailing edge stock and make a new aileron. Trying to straighten warped stock is hard to do with 100% accuracy. Once wood has warped it will always try to find its way back to the lumber yard by warping again. The cost of replacement will be small and you won't have to worry about it in the future. The other alternative is to ask SIG to replace it.
Watch the weight distribution on your LT40. They tend to be tail heavy. Balance is critical but they do fly nicely.