An uploaded gif represented as a static image on my page was missing some data, resulting in white spaces. Turns out they were all 000000 black. I was able to get around the problem by coloring them all a slightly lighter shade of black and fooling the system. But it knew :)

The next time the graphic loaded (looking fine) this error came up: Warning: imagecolorsforindex() [function.imagecolorsforindex]: Color index 127 out of range in /home/tercar20/cleanwhiteroom.com/concrete/helpers/image.php on line 136

It doesn't appear on subsequent reloads, but with each new graphic I use this trick on, it lets me know.

Thanks, C5 team :)