While You Were Away...

When our kids are away from us, we worry about them a great deal; I have adult children now so I am somewhat "accustomed" to my being away and not calling everyday. However, my 12 year old recently left for a couple days and she hardly called at all; I may have received a text from her asking to stay longer but that was it. Although I was in constant contact with the mother of her friend, I didn't hear from her too much. This really bothered me because I usually don't allow them to sleep over but we have spent a lot of time with this family and I was okay with her going. When she returned home, I spoke with her about at least checking in with me periodically while she is away. She didn't see anything wrong with it; she said she was having so much fun that she wasn't thinking about calling me. I reminded her how important it was for her to check in with me; I also reminded her that if she couldn't do that then she would not be staying over again. I think she got the picture!
If you are a parent of a tween like I am, or you have teens, how have you or how would you handle a situation like this?