I got it through "check updates" too, after reading about it here. It was the new final step, added after the usual two checks (and downloads) for defs.
I suspect they might have upgraded the update-check process in the previous, quite recent, program upgrade, although I don't remember seeing any mention of that in their "what's new" thing. I too always had to get upgrades from the site before, and that one in particular needed a full uninstall-reinstall.