They will not set off the metal detector. However, they will show up on the xray machine. The metal detectors look for iron in magnetic metals. Thats why gold, stainless steel, titanium body implants and such dont set off metal detector. Besides, there is very little metal on the tops of your vials.
But that aside, i would mail them, or put them in bottles with screw on tops. Label them massage oil. You can even get screw on tops with a septa in them (the rubber thing that you stick a needle through)