An update on my situation.
One, I found this thread: highdefforum.com/verizon-fios/33131-hdmi-frame-loss-vs-component.html
, which seemed to have some thoughts that the FIOS box could be to blame somewhat - but I've no idea if the problem described is the same or not.
Originally, I'd gone with the HDMI cable that came with the TV, then switched to another one I'd ordered via some links from an article at CNET saying they didn't think high dollar HDMI cables did much of anything worth the money. No difference with the two cables.
I did try changing the video format on the FIOS box, but none of the settings mattered - the problem still occurred. (Last night the problem seemed to be pretty bad - it seems to be getting worse - esp. since I don't recall having it at all for at least the first week or two owning the Vizio TV).
I tried rebooting the FIOS box - that didn't help.
I've opened a support ticket with Vizio, but they've only gathered routine order data from me, no real help yet.
So ... I realized the TV has 3 HDMI plugs, what if I try the HDMI 2 or 3 input? When I first plugged it into HDMI 2, I swear it had a small bit of the problem, and then ... the rest of the night it was fantastic, not a single picture glitch.
It is a refurb TV, so maybe the HDMI 1 plug has something wrong with it?