Reactions had been reported to Amy's GF Mac & Cheese. The culprit has been found.
"They followed the corn trail and discovered that the company that makes the macaroni was making products that contained corn on the same line as the rice macaroni."
According to the poster, Amy's has had the company put the GF pasta on a separate dedicated line so this should no longer be an issue in the future.
Do use caution though until the corntaminated packages are off the shelves.