1.6.3 was released back in January with lots of fixes. Renamed 1.6.2 ebuild worked fine.
Thanks for the report, in fact I updated it when I saw your comment on bug #493410 ! *argyllcms-1.6.3 (28 Feb 2014) 28 Feb 2014; Bernard Cafarelli <voyageur@gentoo.org> +argyllcms-1.6.3.ebuild: Version bump, mmostly bug fixes