Im sorry, its not something Ive been aware of. The site is monitored by both montastic and Pingdom - Neither of which emailed me any reported any issues. If the server was down then I should have also got an error on via a program running on my local PC which checks the server every 10 mins. No reported errors there either.
That said Ive been out since early o'clock and just got back so I cant speak for first hand experience. Any one else notice anything?