Appearing in a mint sealed INSPECTED package adds significantly to the value of your coin. Never open the packaging to answer anyone's questions. I personally found a mint set where the dime was struck on a metal scrap. I sold that mint set to a mint set / proof set specialist dealer over the counter for his first offer of $4000. I did not tell him that he sold it to me in a lot of ten common mint sets two years earlier. We both assumed that something common was worthless. He aggravated his mistake by not examining something before he sold it. I examined them only to insure that the coins inside matched the date on the outside of the envelope. Once I looked it was obvious.
Water is more dangerous than grease - it can crack a die or collar - it has surface tension missing in oils..