Don't get me started on graphic designers and digital photos. I had one guy I worked with all the time at a good sized design house who was always getting colours off. I asked him when the last time he profiled his monitor, and he didn't even know what I was talking about. I went over and did a profile on his monitor, and that fixed things a lot.
Possible problems are that either you or him have an incorrectly profiled monitor, he might have converted the image to CMYK, and that's caused a colour shift, the colour spaces are different, maybe he's got a big bank of flourescent lighting in his office that's screwing up what the monitor looks like. The list is endless. My advice would be to go his office and look at the image on his monitor, and go from there.
David Buzzard's Technical Blog