Why is she sending so complicated signals?

So there is a girl I've been friends with for a few years. Nothing special and romantic whatsoever. But last year she started getting closer -- we went to some museums and restaurants together, she was at my house for a few times, she started sharing my interests, telling me more about her. It looked like she is interested in me in a romantic way (we wanted to go to a trip together, she asked me some intimate questions and once, as I said that my flat is filled with her perfume, she replied that she is just marking her territory). My friends, who knew about it, said it looked like she is into me.

But recently we had a chat, and she advised me to find a girlfriend, cause "you are almost 30, it is time". We are both sngle. I joked that she would be the perfect choice, and she responded angrily that we are no more than friends, and I shouldn't have any plans for that, because she only sees me as a friend and her friends are making jokes that I am in love with her, and she tortures me. I apologized and confirmed that we are indeed friends and I didn't mean anything. She said that it is good we made this all clear.

Out communication hasn't changed still, we are still friends, but I am wondering what is going on? Maybe I was misreading the signals?
Why is she sending so complicated signals?
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