Slick2D diagonal line artifacts

I am using slick2D but whether draw something on the screen myself or load an image, there is a diagonal line that runs from the upper left corner to the lower right. Please see the screen shot here.

The rectangle was made with g.fillRect and the images are both pngs (and the diagonal does not appear in the source image itself). I googled around but could not find anything matching this problem. Has anyone else had this issue before?

Looks like the effect that happens when you enable anti-alias on the Graphics object.
If you are, try disabling it before drawing images.

That did the trick. Thanks!