I am really hoping that it is not mold...I'll find out when the seal busts or I am ready to smoke it, ha.
But yes, it is interesting which tin bulge and which don't. I bought a ten year old tin of Opening Night and it had a slight bulge. That tobacco was beautiful to look at and smoke (smelled like a nice Abbey Ale), so that was my expectation of aged Opening Night. I then purchased a 7 year old tin (no bulge at all), expecting more of the same. It was almost like it was a different tobacco (not a flake, more bright yellows than reds). I have intentions to start a new thread regarding that tobacco, with pictures (maybe tonight).
But I'll upload the bulging Gaslight picture later. For some reason my phone wants to turn the picture sideways when I upload it right now. Either way, those flavors will surely age well.