Asking for A-1 sauce or any other condiment for your steak can be seen as a personal preference, and it is generally not considered rude to do so. However, the appropriateness of the request can depend on the context and the type of restaurant you are dining in.
In fine dining establishments or restaurants where the chef takes great pride in the preparation and flavoring of their dishes, it is generally preferred to taste the dish as it is intended to be served before adding any condiments. Some chefs might feel that adding sauce to their perfectly cooked and seasoned steak is an indication that their culinary skills are not appreciated.
On the other hand, in more casual dining settings or family-style restaurants, it's more common for customers to have the option to customize their dishes with various condiments, including A-1 sauce. In such places, it is perfectly acceptable to ask for A-1 sauce or any other condiment to accompany your steak.
Ultimately, the best approach is to gauge the ambiance and style of the restaurant you are dining in. If you are unsure, you can politely ask the waiter if it is customary to have condiments with the steak. Additionally, if you do ask for A-1 sauce or any other condiment, it's essential to do so politely and with respect, acknowledging that the chef's expertise is valued, but you simply have a personal preference for the sauce. Most restaurants will be accommodating to their customers' preferences, so as long as you are considerate in your request, it should not be perceived as rude.