Does heat damage cosmetics and makeup during the shipping process in the summer? How about vitamin C serum and shipping in the heat? what about eye primer shipped in the heat, still any good?
Every reputable cosmetic manufacturer stability tests their products under high heat conditions. (Usually up to 113°F for a few months.)
So under normal conditions of shipping you should have no problem. However the weather in some parts of the US has been so hot this summer that there's no guarantee product's weren't exposed to temperatures way in excess of their usual limits.