I have had this happen twice on customer's quilts. Once right at the outside edge and once within the body of the quilt. Both times it was advancing the quilt with the needle in that caused the problem. I called and apologized to my customers. The hole at the edge was easily covered with the binding. The hole within the body of the quilt I fixed by fusing the fabric to the batting then sewing a appliqued butterfly (it was a floral quilt so the butterfly looked very nice. Each customer was very pleased with their quilts and I have quilted several for them since then. I just feel when I make a mistake I must owe up to it, speak with the customer about it and correct it the best I can. I would certainly contact your quilter again and give her another chance to fix the problem.