GTI's with xenons the lights turn as corning lights.GT's use the foglights as cornering lights.GTI's were people have changed the setting in VAGCOM/VCDS can have cornering lights like the GT's using the foglights.
Never seen a GTI do that unless someones set it. Its not listed as doing it in the VW broucher either unlike the GT.Your dealer must have set it like that when they took the car out of transport mode during PDI.