Our Firebrick rebooted itself around 00:26 this morning so data from midnight to then will be lost on the live graphs and the daily ones.
The daily graphs for yesterday should be there.
We have a system that backs up the data hourly from the Firebrick so although the 'live' graph may be messed up if there's an issue (the Firebricks lose their data on reboot and the live graphs come directly from there) the past days' ones will just have a gap of up to an hour.
Not sure what caused the reboot but some kind of kernel panic.