High CPU utilization on standby F5 LB

Hi there I've experienced an unusual event. One of the clustered loadbalancers operating in standby mode has reported a very high CPU utilization (99%) which lasted for over an hour. Logs have been checked and nothing suspicious was found at the time when this event has had occured. The only line in the logs which could have been associated with the issue is "Sep 30 09:30:34 notice clusterd[5873]: 013a0006:5: Bumping this blade's revision and saving cluster config." After this event there is a big gap in the logfile. After one hour the loadbalancer came back to normal operation. Just wondering what could have caused such condition. Any thoughts ? Regards