'Degraded' RAID Status Question

I have two SATA drives set up in (mirrored) RAID 1, and the following status message is displayed: (I am using hardware RAID)

I recently noticed that their status changed from ‘Healthy’ to the ‘Degraded’ status that can be seen above. What does this mean?

Normally, I would assume that one of the drives had failed, but both of the drives themselves are reported as healthy. Also, I haven’t noticed any data loss. Any ideas?

Thanks for any input.

Edit: I just noticed that two drives show up instead of the regular one logical disk presented to my computer.

Edit2: I am guessing that I can just break the mirroring (unless it’s already broken, since it looks like there are two different mirrors there) and rebuild the 2nd drive based on the contents of the first drive. Does that sound correct?