When does sharing mean I get something?

Norah had a day-long lesson on sharing today partly from Lindsey and partly from Elmo. So tonight Norah decided that sharing should be a two way street. I usually sit in Norah's room while she is falling asleep and surf the internet on my iPod. I turn down the brightness to try and keep a low profile but tonight she spotted me using my iPod. It took me a while to figure out what she was saying but eventually I figured out she was saying "share." I felt really bad that I couldn't share with her when she had been forced to share all day. I guess I just completed her teaching about sharing. You only have to share when you're a little kid and adults force you to--once you're older you don't have to share anymore. So sad to have to learn that at such a young age.