What does "cat" mean? Was the next file "bnc.jpg", "grep.jpg" -- even if it had something to do w/ felines -- was it in a dir of gfx of DNA visualizations, where the image would be a GATACA sequence or something? I don't know, but these are questions that immediately come to mind for me.
There's no mention of what the filename was. Neither the basename, nor the extension.
My comment merely quoted a 37signals employee giving the filename, both basename and extension. You can believe them or not, but they did explain the situation, and they explicitly denied looking at the image.