What does it mean when a guy calls you "Hun"?

There's a guy who I've known for six years. We are very close . We talk about everything, He is always there for me when I need someone to talk to. He is always concerned about me. We text each other all the time. He always tells me to get on the computer so we can talk. But for the past few months, I have noticed him calling me 'Hun". I know 'Hun" is a term of affection. I know a lot of friends say that to one another. But he doesn't call anyone else "Hun". He'll say things to me like "I miss you, hun", "How was your day, hun", "We need to hang out, hun". I was talking to him on the computer earlier today. Before be got offline, he said "Night, hun. I love you." He has never told me he loved me before. He doesn't tell other friends he loves them. Sometimes I have a feeling he likes me, but other times I'm uncertain. Should I be concerned? What does this mean? What should I do?