The ignitor is a piezo spark producer and these things eventually go out over time.
When the button on a Piezoelectric ignitor is pressed, a spring-loaded hammer strikes quartz in order to create a spark. This is the typical process used in such lighters. This creates the necessary amount of voltage to generate a spark.
Also, over 8000 feet a Piezo lighter may not work do to the fact that butane boils at 12F when at this altitude. Maybe it is not the piezo that goes out, but it is a butane lighter.