I've recently done this too. I made a quilt for an elderly neighbor who moved away so she would have something to remember me by. I know she will absolutely love it and would never notice the loose fabric in the backing, but it really bugs me. She and I did a lot of crafty things together when she lived here and she was not a perfectionist by a long shot. I know what I did wrong and will do better in the future (I hope!). I don't usually quilt anything larger than a crib quilt but didn't want to take the time to send it to a long armer. I laid it out on a sheet on my driveway and spray basted it, smoothing each layer as best I could. I forgot about reading that others tape the backing so it won't move. As much as it bugs me, I'm going to leave the puckers there and tell her it's not my best work, but I did it with love.