On Mon, 2 Mar 2015, Wilson, Jonathan wrote:

While the monthly scrub was running the following errors (at the bottom
of the post, copied from syslog) were issued.

As soon as you get UNC, it's the drive reporting that it can't 
successfully read a sector. Usually this sector is then reported as 
"pending" in your SMART output.

Since the log you provided shows a lot of sectors being corrected and you 
after that have 0 pending sectors on the drive, I'd say you are now fine. 
I would run a new scrub manually in a few days just to check, but you 
might be fine going forward. There is no really good way to know, but 
generally, a drive that throws a bunch of UNC should be monitored so this 
isn't becoming a common problem. I tend to replace drives that have thrown 
these kinds of errors if it happens on any kind of regular basis.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se