I have the same issue, again no changes to my site.
It's possible that this is caused by the Christmas season, I'm noticing some crazy errors popping up else where on the web and with my Internet connection.
Here is the error message (if it is any help)
SQL ERROR [ mysql4 ]
Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (13) [2002]
An sql error occurred while fetching this page. Please contact an administrator if this problem persists.