Customs doesn't know what's in the package unless they open it so I would say your good. Also it's not illegal to have the vials do even if they did happen to open it there isn't shit they can do.
Sorry but every package coming into the US requires a Customs declarations for its contents. Given, bringing a small amount of anything into any port of entry is not a big deal. Walking across the border, flying in, cruiseship, whatever...bring 5 glass dragons from China and no big deal. Now try and bring in 500. Customs will automatically qualify that as a comercial entry and require you go through an import process.
In this case bringing thousands of bottles from Asia will require you to comercially import them and pay any duties/taxes that apply and you will be looking for a customs broker to help you with the import.
The govt.does know whats in a package whether they open it or not when it comes to comercial entries. Having imported for years from Korea and China via ocean container and air freight there is a process in the entry of foreign goods which includes declaration and clearing of comercial merchandise.
Forgetting all the hoops for a large order of vials, quality control comes into play. One of the biggest problems being that if you receive damged or unacceptable items...what are you going to do? Export them back to China? I know the price point for Asia is attractive but there a ton of things to consider.
Either way good luck!