Trying to ask a girl out, after a somewhat big mistake?

I'll try to make this as short as I can. I meet this girl in my math class. She began to show all signs that she was interested in me from laughing at whatever I say to staring at me (I can see that from my peripheral vision). So I asked her for her number she happily give it to me. We texted back and forth, but there was not flirting exchange, was to scared to start one. The mistake I made was when she texted me about how her new iPhone 6 was beautiful and what not. So I replied back with "just like you. ". Thinking that it would be both funny and a bit flirty. Now looking back at it not my smartest moves, since there was no previous flirting exchange, by me doing so I'm coming out way too strong. Of course she didn't reply, nevertheless, I prepared to get rejected or be called a creep. But to my surprise she didn't mention anything. Instead she was her normal self. So I didn't mention the text message. Now I fear of complementing her or taking it any further.

What should I do now? Is she still interested in me? Why didn't she say anything about the text message? Have I just screwed myself?

Please keep in mind, that I have no experience with getting a girlfriend before. This is all new to me.