Let me tell you that once she excepted the keys and signed the book its on her. If you took or didn't take the narc she excepted the keys and now its her responsibility, not yours.
Usuually the out goiing nurse will have the book and the incoming will have the pills to count. Depening on where you work the way its done varies. Where I work I count the cart by myself and so do the other nurses unless you don't know or trust the person. If for some reason the nurse forgot to sign for a narc you will just flag it for that nurse to sign. But I will tell you that you can not trust every nurse. Nurses are said to be the biggest drug abusers, because they have acess.
Rule of thumb ALWAYS CYOA= cover your own A_ _
Do remeber in it all narcs are a federal offense. Remeber all the time, money and sacrafices you put into becoming a nurses and not let anyone jepordize your license.