Is it an issue that they've mentioned or just something that's come to mind as a potential issue?
Personally, I wouldn't stress over it.
If you still do, produce the same design in a brief range of colour-schemes and let them choose (read: take the blame).
As long as you're not designing with an overtly nationalistic or race-related colour scheme in mind, then I'm sure the job will turn out problem-free on that score.
The more you concern yourself with it, the more likely you are to be reacting in favour or against certain schemes based on their possible, unfavourable interpretation. Allowing yourself and your work to be effected by that kind of reactionary pressure goes against the ideals of race not being an issue whatsoever.