Mistaken identity

I was at Arby's yesterday with a friend. We ordered and they were running behind on my friends fry order. A few minutes after we had sat down a person brought him his fries. I was taking a bite of my sandwich as my friend said thank you sir. I still hadn't looked up at this person but I would have bet my wife's new van that it was a lady. I said you mean ma'am. My friend then says sorry to this person. After I said those words I looked up and saw to my horror a young man delivering the fries. What do you say at that moment? Sorry I thought you were a woman based on your voice. Then another thought popped into my head. What if it is a woman? Do I insult her? I learned a lesson yesterday. First of all, always look before speaking. It is a good rule of thumb. Secondly, I need to be careful with folks. Here is a young man....I think who could be hurting because of my carelessness. Is it kind of funny? Yes but not to him. How often do I judge someone based on the sound of their voice? By the clothes they wear? By the company they keep? I need to look deeper at a person than just the surface. Point taken.