Is it normal for me and my friend to sext?

Well just last night I had come home from a dance performance i had to see for one of my classes. I texted my friend and told her about it, and described it as beautiful. She replies telling me I'm beautiful. It was just a nice compliment from my friend, I didn't think too much of it (she's mentioned possibly liking girls before, but had a boyfriend for three years that she no longer is dating). So I tell her she's beautiful back, and I send her a picture of me blowing her a kiss. She sends back a picture of her without a shirt on and in tight pants. She looked so sexy, so I was telling her she's hot as hell, still not thinking much of it. She starts telling me how hot she thinks I am, and send me a picture of her in her underwear. Naturally, it turned me on like crazy, so I sent back some pictures of me in just a thong, back turned to the camera. My face is in none of the pictures i sent her. I'm saying "wait when did this get so sexual lol" and she goes i don't know but i like it... And we're getting really into it, and even though it's fun and playful, I'm still laughing, thinking what the fuck this is my friend who i've never seen in that way and never thought she saw me like that either. I say " i kind of wish you were here right now" and she goes "i would kind of really like that". I'm at school, and she lives back home near me, and long story short we plan on fuggin next weekend. I'm not really sure I need any advice, I'm pretty sure this isn't normal for two friends, but i guess since we have similar sexual preferences and just so happen to be attractive gals, it's normal in this circumstance? I don't usually see my friends as romantic or sexual potential (at least not openly). Also, I'm 18.