Glad it didn't cause any major damage. I suspect a case full of our Lipos could cause some real damage.
I can add another place not to store your batteries. In your pocket

Not exactly the same but I work in an ER and yesterday had a patient come in due to burns on his leg from a lithium ion battery. An extra battery for his "vape device". Must have shorted on something metal in his pocket and caught fire. Second degree burns to his thigh and behind his knee. Earned him a burn unit admission