So, since I haven't checked my cellar in a while, I gave it a once over. Like mentioned in my previous post I do it about once a year. Usually, to remind me what I have sitting around. This thread was a good reminder to take a look.
I currently have 17 square tins in my cellar (mostly Samuel Gawith), and they range from 2013 to 2017 (production date), and all and the seals are all intact. I have 35 round tins of the same style (mostly Dunhill and Hearth & Home blends), and they range from 2012 to 2023, and all the seals are intact. I have 32 round tins of the McClelland, C&D, GLP style, and they range from 2012 to 2018, and all of their seals are intact.
I see no issues with any of my tins except one Dunhill tin that has a dent on the top edge, and looks like the side is pushed out a bit (like when you put your pipe tool in to pop it open), but the seal is still intact. I have one Seattle Pipe Club tin that some stuff on the bottom that looked like it was rusting through, but the stuff flaked off. All appears well with the cellar at this time.
Since I was going through the cellar I figured I'd pop a tin of something I haven't had in a long time. I pulled out a 100g tin of Mac Baren HH Highland Blend (which was discontinued in 2013). I bought a few tins knowing it was going to be discontinued, so this tin was from 5/9/13. It had that sweet sound of the sealing popping, and the tobacco was in ready to smoke condition. So everything appears well in my cellar as it sits currently.