Looks like a flying saucer.

 

Were you close to Area 51, Big Echo?

Seriously, that's a first. If it happens again, seems like a dealer visit is in order and ask OnStar if they are seeing any errors (doubt it). If they are ask them to email your the report of course.

 

Told you not to keep those shrooms in glove box.

 

Looks like Wavy Gravy's screen saver. (ok, I just REALLY dated myself there).

 

Well when my tablet or laptop does such thing ...it does portend to failure in the future (loose contact or dry solder most probably). hopefully it happens with repeatability in warranty.

 

I don't think I would worry. Restarts fix software problems. Likely not indicating a future failure.

 

Gocheif:
Thanks for getting back. It has been eight days since my screen gave me the rainbow look. Hasn't come back again. I also get the feeling it was a spurious software glitch. But as others have posted, a couple of times through the years tablets of mine have done much the same. Except the screen would exhibit a lot of small straight lines across. In those cases, a knuckle rap on the screen, or a bit of twisting of the tablet would prompt the screen to go normal... for a while at least. Which indicated a bad connection inside. For my Equinox EV, time will tell!