The 3ware RAID controller detected an unclean shutdown of the operating system, either from a power failure or improper shutdown procedure. The controller will force the unit to begin verifying, due to the possibility that data on a redundant unit could be out of synchronization.
To prevent unclean shutdowns, always go through the normal shutdown procedure. It is also recommended to use an uninterruptible power supply (UPS) to prevent unclean shutdowns due to sudden power loss.