O MySQL reiniciou-se após funcionar bem por 230 dias. Por quê?

Question

Eu tenho um servidor MySQL que está funcionando perfeitamente por 230 dias. Então, hoje cedo, o MySQL pareceu se reiniciar do nada.

O log de erro do mysql tem apenas isto:

131126 17:04:40 InnoDB: The InnoDB memory heap is disabled
131126 17:04:40 InnoDB: Mutexes and rw_locks use GCC atomic builtins
131126 17:04:40 InnoDB: Compressed tables use zlib 1.2.3.4
131126 17:04:40 InnoDB: Initializing buffer pool, size = 500.0M
131126 17:04:40 InnoDB: Completed initialization of buffer pool
131126 17:04:40 InnoDB: highest supported file format is Barracuda.
InnoDB: Log scan progressed past the checkpoint lsn 1094802773598
131126 17:04:40  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
InnoDB: Doing recovery: scanned up to log sequence number 1094808016384
...
InnoDB: 1 transaction(s) which must be rolled back or cleaned up
InnoDB: in total 3 row operations to undo
InnoDB: Trx id counter is 135CA8E00
131126 17:10:58  InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percents: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 4$
InnoDB: Apply batch completed
InnoDB: Last MySQL binlog file position 0 709588816, file name /var/log/mysql/mysql-bin.000808
InnoDB: Starting in background the rollback of uncommitted transactions
131126 17:11:25  InnoDB: Rolling back trx with id 135CA8B20, 3 rows to undo
131126 17:11:25  InnoDB: Waiting for the background threads to start
InnoDB: Rolling back of trx id 135CA8B20 completed
131126 17:11:25  InnoDB: Rollback of non-prepared transactions completed
131126 17:11:26 InnoDB: 1.1.8 started; log sequence number 1095025187164
131126 17:11:26 [Note] Recovering after a crash using /var/log/mysql/mysql-bin
131126 17:11:40 [Note] Starting crash recovery...
131126 17:11:40 [Note] Crash recovery finished.
131126 17:11:42 [Note] Event Scheduler: Loaded 0 events
131126 17:11:42 [Note] /usr/sbin/mysqld: ready for connections.
Version: '5.5.29-0ubuntu0.12.04.2-log'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  (Ubuntu)

O servidor não estava sob qualquer tipo de estresse que podemos ver. Usamos o ServerDensity e temos procurado na história e não encontramos nada fora do comum.

O que pode fazer com que o MySQL se reinicie assim? Quais arquivos de log devo verificar para obter uma pista?

Editar

• Não encontrei nada relevante em dmesg ou syslog