I too followed the book at first. It wasn't until I watched a Momma hen with her chicks that I realized they're tougher than we think. It's a great thing to experience and a wonderful way to have chicks raised up.
Our hen is very protective the first week. (like extremely) As the weeks go on she settles and gives the babies a little more rein. As long as your hen is not pecking her young I would say thats good behavior. She is probably going to puff up at you and the rest of your flock for a while...