I created a series of images with a radial gradient background. It was smooth yesterday when I created the gradient but today when I opened the file again, it had a circle shape right in the middle. I've try playing around with the gradient to see if I just had to smooth it out but nothing works.
When you select it with the black Selection tool, and you look at the Gradient panel, do you see 2 stops (dark gray to light gray) or 3 stops (dark gray to light gray to dark gray)? To remove a color stop, drag it downwards until it disappears.
Also: does it print smoothly? Does it look different if you zoom in or out? Is it RGB or CMYK?