Why is my Fujifilm Finepix F850 EXR LCD image vignetted?

Why is my Fujifilm Finepix F850 EXR LCD image vignetted?

I just purchased this used (although it appears brand new) and upon starting noticed that the corners of the LCD image are darkened, sort of a vignetting. Looks like something internally is cutting off the corners of the image. Other than this, the camera works perfctly. Any ideas? Thanks