I've been dating a girl on and off for about 7 months now. We're currently not dating and the past few days she has acted as though she has no interest in me anymore... Until tonight.

Her and I were talking on the phone as we do about every night, and she started really warming up to me, talking about how horny she was and such. I didn't know if she was shit testing me, so I played it cool and just seen where it went. Eventually she started asking me if I was horny and such, so I took that as a sign that she was really wanting to.

We were kind of limited to our options tonight, so she went with phone sex, and we were off... Thing were going awesome for about 20 mins, without thinking too much about it, I said "I think about you all the time"... Click. She hung up on me.

I waited a few mins to see if she was gonna call me back, in case it was by accident. She didn't, so after about 5-7 mins I texted her simply asking "did I say something?" and she replied "yes."

She went off on me a little bit about the "I think about you all the time" line, and I plead my case that I didn't mean that to come across the way it did, and she knows damn well that I'm not a perv. I've never asked her for anything sexually since we've known each other, and she's treated me to a few things on her own will. I just feel like an idiot, and said something without really thinking about it and how she might have reacted. It just sounded good in my head, and out of my mouth it came.

I apologized and said I was sorry, she said she was upset and that she would get over it. I just can't help but think if this hurt my chances at all of getting back with her. Is there anything I can say tomorrow when we talk again (hopefully) to maybe mend it, or should I just not mention it again, and let her get over it?

Some things happen for no other reason than to teach you to not do them again. Everything you say over the phone should have the goal of increasing her attraction for you. I keep phone calls short for this reason. You want her to have limited accessibility to you so you're in high-demand. Also, if you keep phone calls short, you can plan in your mind exactly how it will go down. I rarely call any girl without knowing exactly what i will say, and what i will say to what she says.
In your case, i would work on inner game before anything else. There isn't any "line" or "routine" that will help you. And i won't lie to you: inner game takes time to develop.

Er, more to the point. I don't think you did anything wrong. It's perfectly acceptable to say shit you wouldn't normally say in the heat of the moment. Don't beat yourself up, the girl is wrong here. She's just dicking with you to keep you under her foot. "she said she was upset and that she would get over it" is a classic form of controlling a man's behavior. I think she just wants you to know where you stand and pounced on the first iffy thing you said so you would have to work for her validation.