What the actual F is this?

I saw this when powering back up my Asus PG32UCDP. It seems like a monitor problem as dark corners look like logo dimming. I had been gaming not long before, so I guess it was temporary persistence -- right? Has anyone seen this before or think it's a cause for concern? The monitor is relatively new (purchased open box from Microcenter).

I saw this when powering back up my Asus PG32UCDP. It seems like a monitor problem as dark corners look like logo dimming. I had been gaming not long before, so I guess it was temporary persistence -- right? Has anyone seen this before or think it's a cause for concern? The monitor is relatively new (purchased open box from Microcenter).