I would call her and ask if she had used all the fabric and if she was going to be able to pay you soon for the fabric used. Tell her you can come by and pick up the unsed fabric and pick up your payment at the same time. It is the principle but also the money. She offered to pay for it and she would of had to if she bought it at a store. Maybe she got busy and forgot or maybe she was trying to get away with something for free. Give her the benefit of the doubt but I would still call her and ask if she had any material left and if she had the payment for you for the rest or the whole thing. If she doesn't pay you for it after that then you need to chalk it up as a lessen learned.