Missing IP?

I had just completed a game of the ARSR mode and it displayed my IP as 12,702. I logged out and logged back in a few minutes later to mess with some settings and it showed my IP as being 12,468 even though I hadn't spent any since being on last. Obviously confused, I re-log to see if it was just a small bug and it showed my IP at 12,702 for a few seconds before reverting back to 12,468.

Just curious to know if this is happening to other people.