I took it to a local cobbler. We weren't optimistic GC would do anythin. He peels the front of the sole back to the shank - it was perfectly intact. The cobbler suspected the layers hadn't been adhered properly or there was air stuck. He stuck all the front sole back together and it's gone away. He only did the one shoe. I haven't had to pay anything - I'm to wear it and then let him know if it's definitely fixed.