My 5S just told me to update to 7.0.5......I live in germany but the patch notes state "improves the cellular settings for users in China"(something like that).
It was released several days ago. The reason you're getting the update is because your particular iPhone model is also one of the models that's sold in China (with regard to the supported LTE bands). My UK iPhone 5S also received the update on 29th.