Delayed anaphylactic response to dairy

Patient: I own a restaurant, and recently a customer notified us that she had an allergic reaction to dairy due to something she ate at our restaurant. She described the reaction as beginning with stomach cramping a few hours after her meal, followed by her throat closing up approximately five hours later. I am trusting this customer who believes our food was the culprit, but I am curious about this anaphylactic response she describes. Does this really happen five hours after exposure?