I had accidentally bought two copies of the same book from Barnes and Noble. I didn't have the receipt anymore. At first they thought I wanted to return it for

I had accidentally bought two copies of the same book from Barnes and Noble. I didn't have the receipt anymore. At first they thought I wanted to return it for money and seemed hesitant but I just wanted to get the first book (I had two of the second). They were really helpful and exchanged it for the correct book. I know it's not too relevant but I was so afraid of a no receipt, tough luck situation. I'm surprised they didn't think I just grabbed it off the shelf and went to the counter. It was just a $10 book and not a TV or anything but it left a good impression.