I just popped my first two tins of Irish Flake with the intent to jar them. When I opened the first one, I didn't get that satisfying vacuum pop sound that I really like when opening a tin. When I got the top off, I noticed that little flecks of tobacco had gotten into where the glue holds the seal together on the tin. Thankfully, the tin wasn't that old, and the flakes still feel very fresh and are nice and moist and intact, so nothing to worry about there, but this is why we are told from time to time to check all the tins in our cellars, to make sure that something like this doesn't happen. Also probably a good idea to check the seal on all your tins when you get them from your retailer as well, so if there is a problem with an incorrectly sealed tin, it can be rectified immediately.