She asked you to call her and you called. She never called you back. She gave no indication why she was calling, what the issue was, and this didn't seem to be anything urgent. She didn't call you back. A little bit of phone tag happening here. It was her turn to call you. Whatever is going on, it must not have been that important. I really wouldn't worry about this any further.
It would surprise me if she turned this into an issue when you see each other, but if it does, just say, "I did call you back. I left you a voicemail. You didn't call me."
Should you have attempted to call her again? No. You could have, but this is not necessary.
Should she have called you back? Yes, that would actually be a good thing to do, especially if she's going to pitch a fit about this whole thing later. If whatever she was calling about is null and void and she no longer needs to talk to you, that's fine. It would be nice if she would have called and let you know either way.
You seem to be a little bit concerned over which phone to call. I usually just call the landline. With one person, it's far better to call the cell. You have no way of knowing which method is best for her until she tells you, and I guess you may just get an earful about it this weekend, but overall, you're fine. You called. you left a message.
It would be nice if she would have left a little more detail on the voicemail. I know there are some people out there that really have a hard time dealing with leaving messages and dealing with answering machines, but if the situation was that important, she could have tried calling you again.