Hissed while playing

So as a lot of people know Freya has never been one to hiss except when she has felt threatened. Well I was just playing with her, she was on her back and grabbing and play biting my hand like usual when I play with her when she suddenly just let out a hiss. Now I don't know if she got annoyed, or upset or what? She has never hissed before when playing like this, so it would be good to know. I did immediately stop playing with her when she hissed, I did not keep petting or "provoking" her after and she didn't hiss again, so I'm not sure what to think.

Cats are much closer to their wild ancestors than dogs, for example. They have only been domesticated for a couple of hundred years, and they prey upon animals as well as being prey. Because of this they can be easily overstimulated and then instinct takes over.

You did the right thing, when she hissed you backed away. You probably didn't annoy her or upset her, she was probably just very much in the moment. 

Please never play with your kitty with your hands, the quietest kitty can become over- stimulated during play and scratch or bite, use a soft toy instead.  

It does very much sound like a over stimulation thing.
My 1yo used to be feral and part of her play sometimes is that she gets too excited, stops dead, lets out a reowr then bolts full speed into the next room and waits there.
I wouldn't worry about, she asked you to stop and you stopped. Als well that ends well.