I haven't been able to reproduce. I think the problem went away after removing some images. But I definitely noticed an off-by-1 problem. Sorry I should've taken more details when it was happening. It might be related to http://silverstripe.org/all-other-modules/show/266319
Yeah, no doubt replacing images will screw stuff up. I should remove that functionality. ImageFields do not have upload folder selection capability, and that will hose everything up.