It's hard to say without physically seeing what you're talking about. Wish you could post a pic of it.
One thing you probably already know is that oil from your fingers can refract light in strange ways on the screen...give it a good cleaning.
I don't have any issues like that on my Z3v, but if it was mine I'd go to the store and see if the other display models have the identical issue, it should be a simple thing to check since all you need to do is turn the display brightness up. If the display unit doesn't have the issue, and you are within 14 days I'd ask for a new replacement.
Having said all that, no two screens are calibrated exactly the same. But bright spots that can easily be seen would prompt me to believe it is not normal.
I have not heard anyone else have a screen panel issue.