I think if it is someone you work with and you get along with them I can understand why you wouldn't feel the need to charge full price. If you want to do a token charge I see nothing wrong with that... but I would definitely tell them that you are giving them a bargain and are not charging full price. That way if there are additional requests you can say "I would have to charge you full for that one, I can't give too many bargains".... unless you enjoy sewing and just are happy to have the fabric paid for. (sometimes I feel that way myself... I give so many away it would be nice just to have someone pay for the fabric)