It may not be drama. She may just be one of those types who don't like to lose people they loved. (My xmas list has 250 people on it, because I don't like to lose touch either.)
It's also possible she is reaching out to the only adult she remembers fondly (if she hasn't seen you in 4 years, you haven't been around to be a disciplinary force, so she may have you on a pedestal).
I had something similar happen to me when my out-of-state-cousin's daughters contacted me out of the blue a few years ago. One has continued to be a friend. The other got mad at me when I agreed with the adults in her life and hasn't spoken to me since. It really could go either way.
Or it's possible she really needs a friend right now. Without talking to her, there's no way to know.
If you don't want to call her back, you might just tell her that you're on Facebook, or whatever. That way you can limit contact and if it gets bad you can un-friend or block her. If you don't know how to set up friend-groups that you can use to limit information sharing, PM me and I'll get you the right links.
So much good luck to you, whatever you choose to do.
---
I had several people ask about the Facebook Privacy stuff, so I'm going to post the links here:
Here are instructions on how to set up friend lists, and how to keep information from them:
http://journal.drfaulken.com/how-to-group-privacy-setting...
I have a group called "limited info" and when I "friend" someone -- for a game or someone I don't know well -- I make sure to add them to this group.
Here's how to use the privacy settings to use the segmented friends groups to protect your family:
http://mashable.com/2009/04/28/facebook-privacy-settings/
Here's an article called "10 Privacy Settings all Facebook Users Should Know"
http://www.allfacebook.com/2009/02/facebook-privacy/
Also, protect yourself from people tagging you (when a 'friend' 'tags' you in a photo they upload)
Settings -> Privacy -> Profile -> Photos tagged of you.:
http://img.skitch.com/20081228-dittfbuqedtp4ctgcng9u9rqmg...
You can even set it for specific groups.
It doesn't catch all photos of you uploaded though. If you have mutual friends who are tagged in a picture that you're in, the mutual friends will still see THAT picture.
http://www.allfacebook.com/2008/12/a-flaw-in-facebooks-pr...
Finally, here's a video that is especially helpful on setting up friend lists:
http://www.infusionblog.com/technology/managing-privacy-s...
Good luck!