Roadrunner ip changes

I've been in this house for almost two years and today my ip address changed with RoadRunner. I only noticed as the router didn't have connectivity this morning when I woke up. A reboot later and I'm on a completely different subnet. I was 65.24.119 but now have a 75.185 address. Interesting that the change of ip address happened at the same time I lost connectivity - you would have thought that the proper use of dhcp would have prevented this from happening. With dyndns.org I can still reach the computer by its homeip.net and that was working less than 20 seconds after reconnecting. Good old dd-wrt!