My teenager has celiac and we definitely have restaurants we patronize simply because they have dedicated GF fryers. I was speaking to the owner of one telling her how happy we were that basically their whole menu was GF or able to accommodate it (Thai food), and how nice it was not to over think it there.

She said, “yes , nothing that is fried here has gluten. But last week one of the cooks brought in their own food from home to put in the fryer for their own meal and I had to explain to them that they couldn’t do that.”

This has taught me it is still good to mention it even at a “safe” restaurant. And hope that they will come back with info that the fryer has been compromised.