I think that command is showing you the total number of hours the system has been running, not the uptime - so it could have been rebooted for patching
[Edit] - Slightly pedantically, it's the number of hours one of the disks has been powered up
That's right. We've got 4 bog standard 750G WD Caviar Blues in a software RAID array in that machine, all powered up for 11+ years, none of which appear to have caught any errors during that time. Pretty amazing.
The OS has been updated and the box rebooted for kernel updates a number of times over the years.
[Edit] - Slightly pedantically, it's the number of hours one of the disks has been powered up