This page shows a graphical background assigned to a table being repeated in each cell. I don't believe that this is an inherited property, the specs seem to show a layered approach for cell backgrounds. I also had a similar problem where a background colour for a table was applied to each cell and not to the underlying table area at all. Probably it's the same thing happening here.
Correct: background-image is not an inherited property. However, I can't see the problem anymore in recent builds: marking WorksForMe. I'm sorry it took so long to get to your bug in my list.
Adding 'verifyme' keyword
Works for me: Platform: PC OS: Redhat 6.2 Linux 2.2.14 Mozilla Build: 2000103108 M18 Trunk Build Marking as verified.