What size is the drive? Some drives (36GB U320 10K, 72GB U32010K, and 146GB U320 10K) are notoriuos for giving false failures and predictive failures with downrevved firmware...update the firmware with the latest firmware update CD (you boot to it, free download, 8.0 I think, and it updates everything in the server except BIOS---RAID controller, ILO, drive firmware, etc.).
If you don't do this, chances are it will happen again soon...I hope you have a RAID 5 with a hot spare---this way, you can lose 2 drives and still be okay. Once a drive "fails" because of firmware, then more tend to "fail" (false), and with RAID 5 and no hot spare, once 2 drives give a false failure, you're dead in the water. Highly recommend to update firmware...
Burt