Personally I would go ahead and make the trip. take your own thread with you and show them what is happening. It could be they used a different thread. Don't leave the store until it is right. Oh and you might want to all ahead and make sure that the person doing repairs is available on that day. I have learned the hard way that before leaving the store after a spa treatment, I take my own thread and fabric and check my stitches and anything that was supposed to be fixed or that I had an issue with when I took it in.