The bow on the asus GTX570 dcii is normal. I'll try and add a picture of mine tomorrow as a reference. I wouldn't worry too much about it, enjoy your build!
CM Storm Enforcer | Asus P6T-SE | Intel i7-950 (stock) | CoolerMaster V8 | Corsair XMS3 12GB | Asus GTX570 DCII | CoolerMaster GX750 | Intel 320 120GB (OS-Software) | OCZ Vertex-2 90GB (Games) | 2x Samsung Spinpoint 1TB (Data)