This sounds exactly as the system is supposed to work. It is not easy to create a custom widget using xibs.
Here's how it works:
Your FeedViewController will preform xib loading for the corresponding FeedView.
During this load, it notices the NearestStoreButton subview. As a consequence, it creates such a view using the - (id)initWithCoder:
message on the NearestStoreButton class. It will not magically notice the corresponding .xib nor the corresponding viewController.
If you need to use a xib within a xib, you need to do the loading manually for all subviews. Keep in mind that you somehow need to create/use the appropriate owners (view controllers) for these secondary xibs.