He calls me "kid"...what does that mean?

I have a guy friend that I kind of like and I think he kind of likes me too. We're ten years apart, he's 31 and I'm 21, but we get along really well. In fact, I helped him decorate his new apartment today. While we were shopping for furniture, a saleslady mistook us for husband and wife and he was totally okay with the situation. He even made comments about our "married" life together in front of the sales clerk. In the past he has called me sweetie, but today he called me kid. Is this a friendly greeting or what is something sweeter? In other words, does he like me as a friend or as a girlfriend?
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He has also told me that I'm pretty and he likes my hair. He was also pleasantly surprised that I know how to take care of myself and I'm very independent. He has also said that I"m not like a lot of girls. Does all this add up to him liking me?
He calls me "kid"...what does that mean?
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