I got one. It stopped igniting. I can no longer hear the pezioelectric spark thingy clicking. I just read the wiki page and they have this to say:
"Lighters with piezo-electric ignition typically do not work or have great difficulty at high altitude, if the striking mechanism is improperly aligned. They are unsuitable for mountaineering or other high altitude applications. The higher the altitude, the less likely a lighter with piezo-electric ignition is to work. Above 8000 feet lighters with piezo-electric ignition are no longer reliable."
nb