re-run sysmerge

[stanl]

Once again I display my ignorance re all things computer related.

I ran sysupgrade this morning and when finished was told I had to re-run sysmerge because of differences between /etc/mail/aliases and ./etc/mail/aliases.

My first stumbling block is that I don't see any ./etc/mail/aliases.

Then, the only differences I see are:

-_switchd /dev/null
-root: slaurel
+# root:

But when I look at /etc/mail/aliases, the file looks the same as it always was with
_switchd /dev/null and
root: slaurel.

What am I not understanding and what action should I take?

Thank you