I'm not sure there is a "norm".
That said, my personal opinion is that if a breeder is going to stand behind their puppy, they should be willing to stand behind that puppy for genetic defects indefinitely. Many genetic defects do NOT show up during the first year. I also would want a guarantee that was not a "replacement" guarantee, but help caring for whatever the problem was. (these are usually up to the price of the puppy) Almost no one will return a puppy they love for another, if they find that there is something wrong with the puppy. Contracts aren't set in stone, it may be that your breeder is willing to negotiate the contract somewhat to make you feel more comfortable.
But I would talk to your breeder about this and ASK her what she would do if a genetic defect showed up after a year. Contracts, especially if you are buying a puppy out of state, are only as good as the breeder behind them. Some breeders will do everything they can to help their puppy owners. (we have one person on the forum whose breeder replaced a puppy at no cost when the first puppy was killed in an accident in the home and that CERTAINLY wasn't in the contract!) With other, not so good, breeders, it doesn't matter what it says in the contract, it is very difficult to get them to even respond if there is a problem.
I think the fact that you have people on the forum who have purchased MULTIPLE dogs from this breeder, and still love her, says a lot. The fact that YOU have spent time talking to her and are establishing a good relationship also is important. At the end of the day, when you are purchasing an animal, there is ALWAYS a possibility that something will go wrong. That's just life.
I hope you get to the point where you trust your breeder as much as I trust mine. There are bad breeders out there, but there are also a lot of good ones. I think that while it pays to be cautious, at some point, you have to trust your instincts, and get on with ENJOYING the anticipation of waiting for your puppy. This is supposed to be fun!