Is it good that my guy friend called me his "sis" ?

Well, me and my guy friend have been friends for a little while. We had like almost a month long period when we were mad at each other, but we're good now. He found out that I liked him more than a friend, he didn't care all that much, but, I stopped liking him, I'm still a little confused if I like him, or just as a friend though. At first, when he would call other girls "rad" or whatever, I would get jealous. Then that kinda stopped, I stopped getting jealous. But just recently on his myspace status he wrote "lindsey's pretty rad" and I got a little bit jealous of that. I wrote on it ":O so how come i'm not included in this?" then my guy friend wrote back, "wow, i didn't think this would happen jasmine your like my sis" so I would like to know... is it a good thing that he called me his "sis"? I love him so much, like as a friend, I even told him that he's like the most important person to me. But I was a little weary telling him that, cuz I didn't know if he felt the same way, like if he felt I was important to him too... So what does this "sis" thing mean ?