GLW are not supposed to have single combs...they should have rose combs....that doesn't mean someone hasn't bred a GLW and gotten a single comb somewhere, but usually rose comb is dominant over a single comb so I would question pure Wyandotte lineage.
I agree that much pink at 6 weeks is suspicious for being a roo.
Oh definitely I wouldn't think it had a pure Wyandotte lineage with its having a single comb, but I'm just saying that a GLW with a single comb(from hatcheries usually) isn't unheard of =P