Flirting or friendly?

At a party recently, I met my friend’s girlfriend. Later, while I was sitting alone, she came over to talk. After that, we were dancing, and she was very touchy — holding my hand, touching my shoulders, letting me put my hand on her lower back, dancing closely with me, and even adjusting my shirt by unbuttoning a collar button. She was constantly leaning into me, as if trying to tell me something. Do you think she was genuinely flirting with me, or could it have just been playful behavior?