Years ago, while talking about QA one of my professors asked in class one day asked how you know if your roof has any leaks and the answer he gave was "You wait for it to rain" ...
Highly improbable that you can produce a highly complicated device or system that doesn't have any flaws, and (no matter how much testing you do) many of these flaws will make it into production. Typically, the major flaws get identified early and fixed rapidly so it is rare that these problems persist for particularly long; but dealing with these problems tends to go along with buying any product as soon as it is released.
While I could be wrong, I suspect that Nintendo will have eliminated most of these issues in the next software update; and the few people who (probably) have hardware problems will be able to exchange their system for one without the issue at no cost.