My header images are getting weird jaggedy lines across them that I can't describe. http://www.boxwrestlefence.com. There's a different image on most of the pages, and they all have the same problem. If you look directly at the image, though, it's fine. I've got Twenty Ten running right now, but I've also got Constructor set up on a local host and it's doing the same thing.
The images are the correct size, and I've tried both higher and lower quality and it's the same. I tried jpegs and gifs. Nothing works.
*Edit* I just checked, and it looks okay on Chromium, so it might be just Firefox.