While doing an inventory of my tobacco today I discovered 3 tins with bulging tops and bottoms. All were C&D blends and all were primarily burley blends. Now, if these were Virginia tobaccos with their high sugar content it wouldn't surprise me if the fermentation went a little wild. But these were all burley tobacco which has a very low sugar content. Several years ago, I had a tin of C&D Burley Flake that was bulging so badly I was afraid it would explode, so I held it at arm's length and carefully popped the top. It was probably the best burley I've ever smoked. I'm hoping that a similar experience awaits me when I open these. But, I can't help wondering why this only seems to happen with C&D tobacco, and only with burley.