MotoWiZIt's strange because the bottom screen is not OLED, si IPS and it shouldn't produce any burins.
In fact that's not noticeable in the picture so try the test.
If it appears even on boot time then, I think, you have a problem with the screen. Send it to a repair centre would be my advice. Perhaps @Blake_ASUS could help a little further and give you ways to test.
I remember that in cell phones there are softwares to remove shadow pictures that stay on the screen after it being displaying the same image for a long period. I don't know if this is the case, or if there is some software to aid or not.
See this Asus page for a breef explanation