You may have gotten the notion from knowing the tied ends of the embroidery thread on the back COULD come out over time. Ever seen an embroidered piece in an antique store that the thread had come out? What I do on my clients' projects is to iron light weight fusiblt web to the back of the block before quilting. It holds the threads forever and just reinforces the block in general. It doesn't take long and just a small step to ensure your project stays pristeen for almost ever. Hope this helps.