Please disregard, this was caused by an oversight on my part... I forgot to enable the ovirt-4.3 repo on the node in question :-( My bad.
This leads to a "Feature Request". What happened was that I updated the first two hosts using yum from the command line, so it was plainly visible what yum was going to upgrade/install. With the last host, I thought I would try upgrading it from the WebUI. The problem is: from the WebUI, there is no way (that I know of) to see what packages are slated for upgrade. I've run into this before when the WebUI shows there are updates available, the first thing I wonder is... what is going to be updated? So long story short, in my opinion, it would be tremendously useful to be able to get a listing like yum list updates produces from the WebUI, prior to hitting the "Upgrade" button.