If one treated their chickens with antibiotics, it might be important to let egg customers know. For example, I have a friend who reacts poorly to antibiotics, and rarely eats chicken or meat because of this sensitivity.
Isn't there a recommended "egg withdrawl" on the antibiotic package? But it was my understanding that these were chicks and not laying hens she was worried about. Antibiotics last 14 days in the human body and are then processed out by the liver and kidneys. (Longer if you are old or very young or have liver/kidney damage) So even if the antibiotics given to the chicks lasted 3 months in the chicken body they still wouldn't be laying eggs, so no reason to notify anyone. Now if you treat your laying flock? That's another story.