Is it possible they are getting reports based on allergies? I once (cringe) alerted a local bakery to their tainted ingredients that were causing illness, only

Is it possible they are getting reports based on allergies? I once (cringe) alerted a local bakery to their tainted ingredients that were causing illness, only to discover years later that it was a food intolerance issue on my side. And--same symptoms as reported in this LA Times article. I've also heard that if you eat a lot of something, you can develop an intolerance to it, but am not sure if that's really true, or under what circumstances.