Similar experience: when I was young I built a website for my brother, it looked great on my iMac when I showed him. He said everyone thought it looked weird that the red of the header and graphics didn't match the background.

On my iMac the jpgs were rendered correctly match the rgb hex of the html/css, but on windows the color space of the jpgs rendered them a more crimson hue. Had I tested on my brother's laptop it would have been immediately noticeable.