It really sucks to lose one.
I recently moved my small stock of backup crt's from the attic to room temp storage. I figure one less variable to deal with. Automobile tubes come to mind - but I suppose back in the day it was no big deal if one failed now and then from the extreme temp variations. I have a sneaking suspicion that repair shops and distributors of tubes often stored them in un-climate controlled buildings. At least that seems to have been the pattern here in WI.