According to http://git.kernel.org/cgit/utils/cpu/mce/mcelog.git there are some fixes/extensions available. Can you please update our snapshot? TIA
You can do it yourself if you like.
FYI I have (build & run-time) tested a snapshot at latest commit d2e13bf0bdc72e9d19d63921056b808d5ce8ef62 for mcelog-1.0_pre3_p20130502 and everything looks good. If you'd like to test locally, all you need to do is rename the ebuild & modify COMMIT= to use the new commit's hash.
+*mcelog-1.0_pre3_p20130621 (10 Jul 2013) + + 10 Jul 2013; Julian Ospald <hasufell@gentoo.org> + +mcelog-1.0_pre3_p20130621.ebuild: + version bump wrt #473254