When a scene fades to black I notice that the corners are slightly brighter (hotter) than the middle of the picture. Is there any way to correct this?

No. And no one really knows for sure what causes it. Or at least they're not saying. Must be an LCOS thing. Some of the Sony's suffer from this artifact too. And it's strange - I'll notice it on some fade-to-blacks but not others.

It is not too bad. I would say maybe +/- 5%. I never even noticed it until one of my friends pointed it out. He is just jealous.

There is no fix unfortunately. Some have the issue, some don't, so it is really hit or miss.