This! I've seen this happen a lot. If you had wired it wrong, it probably would have failed right away.
I've heard that Autozone, Advanced Auto and Orielies all buy components that won't pass the big three automakers tests. They still work and sometimes they work for many years. But there never as good as the ones that pass the more rigorous tests. That's why it seems like new cars components last. (This is true of starters, AC components and other stuff)
Of course you get the lifetime warranty. I understand they bank on you getting rid of the car before it fails.

