Thank you for the warm welcome!
After MUCH more Googling, I found some others who had this same problem. They suggested to tap it on a table or clap the back of the iPad. Crazy, right? But I tapped it three times, then clapped it on the back. And voila! Beautiful intact colors again. right?
I already have an Otterbox defender case on it, but lesson learned: no more letting the 4-year-old carry the iPad around! Until recently I only allowed my daughter (almost 5) to use the iPad while seated on the couch, and never to walk around with it. But lately I have become complacent. No mas!