My partner has a mustard allergy, it’s not that uncommon but we normally have it in such small quantities that people with mild allergies brush it off as indigestible or nonspecific itchiness.

I haven’t heard of a celery allergy (those folks should definitely refer to themselves as celeriacs) but food intolerances are pretty varied and wide spread.

I’m hoping that these extra allergens providing market pressure along with regulations might help reduce the crazy artificial additives - American packaged food is absolutely terrible for you in ways we’re still discovering.