Ned gets out of the bed, post-coital, sweaty. He goes and stands in front of the open window and thinks about how much he likes the sharpe cold air and goosebumps come up on his skin. Catelyn tells him to come away from the window before he catches cold. If he's not naked in the book you have, then its been heavily censored. BJ just finished reading that part and he's naked in her Dutch version also.