My old Silver Swirl (bought either in Norway or Greece, most likely Norway) also had curls, and her curls were pretty tight. Also, if you'd straighten them I think they'd not be the same length as her usual hair; I've always thought it was deliberate, that there was a curly-haired variant. I've got no proof though. I never got those kind of curls from any of my other G2's, I played a lot with Silver Swirl (I loved her fiercely) and her curls stayed put.