Since the array is utilizing RAID-1, does this suggest the RAID contoller is going bad?
Could be. I'd recommend you raise a support call on this one. The support guys will probably ask you to run the hardware diagnostics tool (shipped on a CD or USB stick with the appliance - though I believe you can also download a new copy from their download site) and this should reveal if you are dealing with a hardware issue on this appliance.
I'll give both a shot!