I'm sorry as well, and agree your work is beautiful. It is worth pulling every one of those stitches out. I'm just learning to FMQ so you posting this was very important for me. I was recently told to hand or machine baste around the border edge inside the seam line so the border would not stretch as it is manhandled for quilting. Maybe that is not true? It seems from all the responses that you don't do that with FMQ.
I think it is always wise to machine or hand baste the edges...especially the closer to the outside that you get. I had even done that, but it was the excess fabric that folded over that caught me. Hopefully, I'll get it all out without tearing the backing...we'll see. Stay tuned.