There was a small frontend mistake with network diff calculations for CKPool Stats.  This will be fixed, but all the stored data is correct, so once the fix is pushed it shouldn't show any interruption in the stats history.
The bug effects the main page updating, so may be delayed a bit for now; the network difficulty number, and the odds of finding a block.
Sorry for the inconvenience, first time handling a new block found that highlighted the issue.