What sort of relationship is this?

Just the other day I was at a training course with a co-worker. I had seen her before but never spoke to her as I had no reason to. During and after the course, we were talking to each other quite a bit. Then I decided that I liked her, but not in the sense that I want to "get" with her.

Since then, I talk to her when I can, and I have to say that I really enjoy every moment of it. I think about her some of the time, but not in a bad way, just in the sense of the fact that she's a nice person. I look forward to seeing her and I guess that I do have a "soft" spot for her, but I don't feel anything sexual towards her. I just really enjoy her company.

Is this kind of feeling common? Who here has experienced something similar? How could it be described?
What sort of relationship is this?
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