Maybe the ones who don't cross over are slouching. :lol: I know that out of all my birds, some cross and some don't. I find that when they're clipped they let their wings droop and then the feathers wouldn't be sitting so they're crossed (if they were there that is). But the ones with all their feathers hold their wings up more and the feathers cross.
A lot depends on how the wings are clipped if they are. Snitch has his two long wing feathers on both wings, they cross in the back. Piper (my new yellow one) the pet shop clipped all the feathers so they don't cross over, and are at the side of his body.
Either way is ok. Nothing to worry about.