If you asked me a few days ago I would have thought I would have as well. However when I go to WhatIsMyIP.com all it shows is a IPv6 address. Previously I had never saw it show anything but IPv4.
My carrier is AT&T. I suspect that since they have one of the bigger customer bases they are close to running out of IPv4 numbers. I can get one for $15/month and that is probably the route I will go. While 80% of the web is probably OK with IPv6, somehow I think that smaller but very useful tools like your probably fall in that 20%.
I will call AT&T support and if I can't go IPv4 without buying static IP then so be it. You might want to do a little research and see if I am right then throw it in the pipeline for next year.