Alice, an Angel Quilt is when someone (also known as an Angel) steps in to send a quilt to someone who didn't receive one from their partner. And that can be from months ago! Sometimes life interferes with doll quilts but I always ask the person to let me know so I can get someone to step in. In my own case life interfered with getting my November doll quilt out due to Hurricane Sandy -- but I my partner was understanding and I have the pieces here to quilt for her. Although since it was a Thanksgiving theme she'll have to save it for some months before using it ... so she will get two from me.
So, in short, an angel quilt is one that is sent by someone to another member who didn't receive one.