That is strange indeed, we have had, well my oldest son, a crap load of that stuff and it never did anything unstable. It was stored in a building that was not heated or cooled, just a building.speaking of Tannerite. I picked up 8 cans at Basspro this summer and was planning on combining a few to blow a beaver lodge on my property. Put them in the garage.....went out to use them and discovered the powder inside had expanded and pushed the lids off every container and pretty much solidified. I suppose it was humidity.....I don't know. Went ahead and tried to use that that was still a powder.......no blow.