For the amount you're talking about it's not a big issue for sport flying. But because you're moving the wing area forward with this change there may be some minor CG issues. If you're being fussy then use one of the online MAC calculators (see the sticky FAQ's at the top of the listings) to find the current MAC and then modify the wing and move the root position so that the MAC is in the original place.

If this will be for contest pattern flying then I'd leave it alone. The slight amount of sweep may well be what helps the model track well in the various attitudes.