Ok, for some reason when those were imported they didn't get a category set. I'll check the import part for that problem.
As far as fixing the problem, on the next version I'm working on, the uncategorized images will show on the main display only. Once you select a category they will not be displayed. There will also be an admin only link that will show all the images that aren't in a category.
I'll also add a maintenance section item that will allow you to move all images in a category (or if you enter 0, all uncategorized images) to another category.