how strange; my buff orpingtons were the exact opposite. At one week the boys had extra long wings, nearly to their tails and their tails were sprouting, by second week wings were even longer, tails bigger, shoulder feathers coming in and combs beginning to grow. At two weeks also noticed that their legs were thicker and they standing taller, more like boys.
I'm watching a batch of EE & OE right now; if they feather the same as the BO then they are almost all boys, if they feather opposite, then almost all girls. but out of 6 different hens, and 3 breeds, then they could all be different!
And on a Marans note, I _might_ have a tiny BCM pullet egg but I"m not sure as these girls are from Dec hatch and I wasn't expecting to see any eggs until June. But it's a lot darker than the sex links that are in with them.... waiting to see if there's another