> You'll know if you're celiac -- "vague" and "nonspecific" "maybe feel slightly bloated" are not symptoms of the disease.

No, that's not true. My daughter has celiac disease; she has a severe version, so we found this out when she was about 4 years old.

However, in later life my mother suffered from serious food sensitivity problems. She wasn't diagnosed with celiac because that was 15+ years ago. Given my daughter's medical history, I'd bet even odds that celiac was exactly what my mother had, even though the serious problems didn't occur until old age. There is a very strong genetic component to the disease. Wikipedia discusses this at length, but I'm certainly not qualified to know how accurate that information is.

So it's quite possible that with less severe celiac, people only have mild symptoms or only develop severe symptoms late in life.

Sorry to quote Wikipedia, they're hardly authoritative, but I think this is a reasonable summary[1]:

   People with milder coeliac disease may have
   symptoms that are much more subtle and occur
   in other organs than the bowel itself. It is
   also possible to have coeliac disease without
   any symptoms whatsoever. Many adults with
   subtle disease only have fatigue or anaemia.

Edit: just wanted to add that information in this field is changing rapidly. When I requested a DNA test for my daughter about 8 years ago, her gastroenterologist was reluctant. He was admittedly quite surprised when my daughter turned out to have the problem alleles. So it's all "relatively new" even for one of the "experts" in the 19th most populous MSA in the United States.

[1] http://en.wikipedia.org/wiki/Coeliac_disease