there`s no real way of straightening it out yourself afaik. i am not even sure if, theoretically, you could bring the board up to temperature and put it back into its mold to restraighten it.
It is what it is, but is there anyway to straighten them out? Mounting some trucks seem to help a bit..kinda.
i'd say your best bet is to check out how they ride. sometimes little warps can flatten out to a unnoticeable point. if they are already warped they might have gone a bit brittle, too. then again, chapman boards are quite hardy. if it works, it works.