Yes just common packaging, and the open time parameter is there so they can ensure that the parts will still reflow properly, as the factory tinning will slowly degrade with moisture and oxygen if it is not protected by being soldered into the circuit. Keep the package sealed till needed, and put dessicant sachets into the bag when opened, nice freshly baked ones that are dry, and seal the bag hermetically with a bar sealer as well.External PVC bags work well, simply put the entire original one in it, 2 sachets of dessicant, and heat seal, easiest using one of those cheap kitchen vacuum sealer units.