Never wake a sleeping baby?

jasieandry

 I used to try to wake lo every two to four hours to eat but now that shes past her birthweight (born 7lbs 6oz now 8lbs) I start feeding on demand, right?

I'm partly concerned because she's such a good sleeper. She only wakes up to eat twice a night for the past 4 nights. Is that normal for a 2 week old? Should I be concerned or just let her let me know when she needs to eat?