Does your menu describe the rub???
Who did she tell everything is fine??? I've gone by tables that server said "everything is fine" asked the same question and could tell by body language there was a problem.
I get requests for steak sauce. Have lost customers because I don't have Heinz, A-1, or whatever. If the steak need sauce it should go back to the kitchen. Occasionally I get a customer that insists they enjoy catsup (ketchup), which is right???
We offer them catsup, W-sauce, or BBQ. If that's not good enough - Well.
Its your store operate it the way you want. Losing a customer(s) over your recipes is a potential policy decision.
In this case I doubt I would respond.
Thanks, come back, bring friends and money!!!