You know when I get that?
If I wake up and the sun's been shining in my eyes as I sleep.
It's freaking terrifying. I find it goes away faster if I hold my pillow over my eyes and block out all light for a few minutes.
I also have normal palinopsia from time to time but for a while I was having exactly what you describe daily. I don't know when it stopped, but I'm sure it'll be back.
If you have a brain tumor, I do too. And if I have a brain tumor, I've had it for years and it hasn't hurt me yet.