Never say never....
It could be that you are having an allergic reaction to one of the ingredients that CX uses.. which one is debatable unless you grab another croissant next time and test it at a lab yourself.
For example, I have no allergy to tofu but I simply cannot eat tofu processed in Hong Kong. Everytime I have tofu in Hong Kong, bam.. I have to rush to the loo (sorry for the gross expression). But tofu in Taiwan, Thailand.. no problem.
Could be you are showing signs of a light wheat intolerance...