I was in the Bourbo-Bunker admiring what I have left of Birthday Bourbon, Not many now , and none to share. Anyway I noticed the corks were raising and there was a lot of pressure on the heat shrink clear plastic at the top. One was up a full 3/16 of an inch. I just gave them a shake and pressed them back down. There is a display of HH products in what used to be the Farmers Bank in Bardstown , It's on courthouse square. I noticed an Elijah Craig bottle in the window that had almost completely blew the cork. I figured the heat and sunlight was causing it. I don't know what to make of this because the Bunker is very cool and unheated.