Chromebook HDMI HDTV Interface

A strange thing happened last night when I tried to use my Acer Chromebook to view a streaming sports event on my HDTV. I hooked up the HDMI cable, turned everything on, and nothing happened. The HDTV displayed the initial screen I get when I turn the Chromebook on but wouldn’t display anything else. I tried turning everything off and back on, unhooking and reattaching the cables, but nothing changed at first. But after 3 or 4 minutes fooling around the streaming event began displaying on the HDTV. But it was different than before. Previously I had to use the cntl-f4 technique to get the HDTV to display full screen, and the Chromebook screen would go blank. Not so anymore. Now I no longer have to use the cntl-f4 technique. The HDTV displays exactly as on the Chromebook. If the Chromebook is full screen, so is the HDTV. And the Chromebook screen no longer goes blank.

I’m speculating that the Chrome OS decided to update itself when I turned on the Chromebook and suspended HDMI transmissions until it was done, and part of the update involved simplifying the interface between itself and the HDTV. Does this make sense? The settings-help function confirms I am running the latest Chrome OS release, but doesn’t tell when it was installed. Is there any way I can find out when the Chrome OS was last updated?