Firstly, you didn't 'lose' him because of your brother. A lot of people call people hun and it means little to nothing. I sense that you don't have that much experience with dating. This is by no means a crime. We all were there at one time. You need to gather up a bit more courage and confidence that comes from experience.
That being said, I hate to burst your bubble. This attention from him might be all to do with being friendly and normal customer service. However, if you want to find out more, you'll need to ask when is his break. On his break, chat him up and ask about his hobbies, places he likes to go..and be a little forward and say that you might like to hang out with him. Otherwise you'll stay in the dark.
You also wrote about this in a previous link and people have answered you there too: