As observed throughout the novel, Dee/Wangero and Maggie has very contrasting views and personalities. We know that Dee doesn't care about her heritage - with the notion that her people have oppressed her, and Maggie has pride and deep appreciation of their heritage. This includes the appreciation of the quilts which are more than just quilts as they have been sewn by hand by the women that have come before them. In this passage, we can presume that Maggie was the one who had slammed the kitchen door upon hearing Dee's request. It is not surprising that we learn of Maggie's real feelings towards Dee's request as she would have had an idea that Dee would not be able to appreciate the quilts as she would.