Comment 2 for bug 1435695

The microcode update bundle (or collection, or package) contains a number of microcode updates. That's the date in the package version (20150121 in this case).

The release date of the collection of microcode updates is independent of the date of a particular microcode update.

There are hundreds of microcode updates in the update collection, with a very large variance in their dates. Some are very new (Intel changed them recently), while others are more than a decade old (they have not been changed since).

The kernel logs data about the specific microcode update it installed. It will never match the package date, there will always be at least a few days difference: someone has to approve each new microcode update for public distribution, prepare the updated microcode collection with all of them, and send it to the Intel website, and that takes at least a couple days.

Run this:
/usr/sbin/iucode_tool -l /lib/firmware/intel-ucode

and look at the dates of each microcode.

This is not a bug.