I bet the reviewer's problem is the color management policies in AI that have options available for mismatching color profiles. That's why some people get the warning box, some don't.
p.s.: You actually have options to ignore, convert or preserve color profiles of opened (or imported) files, but this is not a solution. I'm wouldn't accept changing global AI policies each time. Those options are there for a reason. And when working outside of the microstock world it is pure nonsense to convert CMYK working profiles (or swatches) into RGB automatically (or the opposite).
p.p.s.: As someone else mentioned in the SS forums: it has to be a jerking issue with someone downloading vectors, seeing the warning and panicking like hell broke loose. There's actually plenty of options to convert CMYK colors to RGB, straight from the beginning. In CS3 you even have an automated action (under edit/edit colors) to convert all selected elements to RGB colorspace (or vice versa).
p.p.p.s.: For f**k's sake. It's an issue with the their repro and printing studios, not submitters. Hell, even iStock doesn't complain about it as far as I know. If they're not able to convert graphics to working/printing color profiles, they shouldn't do their job in the first place.
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One problem I've noticed in CS3 is that the chosen color profiles don't get embedded in AI8 EPS formats. Can't say why, but this could be why the issue occurs. If that can be called an issue.