Comcast has a massive address pool, and has been known to move addresses around when doing maintenance or if they need more addresses in one area that aren’t being used in another. It’s not uncommon for two different routers to pull two different IP addresses in two different subnets either.
Also, geolocation of IP addresses isn’t an exact science, so it may take a few weeks, or even a couple months, for an address’s location to be updated by the various companies that provide geolocation services.