One side of me thinks it was like a 180 flip to her. She saw you as a friend in a friendly environment. The other side of me just sees her as young/shy/reserved because she blushed bright red at the end.
Women are naturally more touchy-feely with their friends, so it's difficult to understand the signs correctly as interest sometimes. Was she touching you? Touching your arms, back, etc.?
Did you ever compliment her on your looks before the kiss? Create any sexual tension?
Example of good interaction. The keys in this type of situation are
strong eye contact, the slow
bedroom voice, and pregnant
pauses with locked eyes.
Girl: "Here, let me show you how to do that better."
*She reaches in front of you*
Guy: "Hey! Are you trying to seduce me? I'm just trying to work on a project here." (Said playfully.)
Girl: "Haha. Shut up! So, you see if you do this and this that it's a lot more efficient."
Guy: "Ah, yes. But, wonder if I do this and this."
Girl: "Yeah, you can do that."
*Pause; look at her eyes deeply*
Guy: "You know..."
*Pause; she is staring at you now; locked eyes*
Girl: "Yes?"
Guy: "....I never realized how exquisite you look....before now."
*Pause; strong eye contact while she responds*
You're just feeling it out. Saying things to probe out her true feelings. Does she blush or voice pitch go higher? Does her facial expression change, etc.?
If it's really good, then you can go for the kiss around there. Else, you can keep creating some sexual tension (with strong eye contact, slow bedroom voice, and locked-eye pauses). Then, if it seems good, go for the spontaneous kiss. When you're new, it'll be hard to feel this out though, so don't feel bad if the girl refuses your kiss and thinks you're weird; you're just learning.
Also, if you kissed in the above example, that would be more of the romantic kiss. The spontaneous kiss is usually never a miss. You're just talking about something, and then you plant one on her real quick, and then go back to talk about whatever. But, for any kiss, there needs to be some type of build up....whether that's verbal (she knows that you're attracted to her) or non-verbal with lots of sexual tension or both (best).
I think that it's good that she blushed. She may be pretty reserved and shy. I think you need to warm this up more, using the above tips. You have to preheat the oven

Actually ask her out on a date; tell her your interest. If she says no, no big deal.