IIRC, I purchased this raft of disposable lighters well over a dozen years ago. One or two I routinely carry in my pockets; when I give them away, lose them, or they run dry, I grab replacements off the basement shelf. Recently a replacement failed to function fresh off the shelf ... so I tested every lighter left on the rack. The disposable lighters standing in the case are still functional. The ones laid flat all failed.
However subtle, time and the physics of entropy are always at work. Sooner or later, stuff happens.