In my smoking days I carried my lighter everywhere and it was very handy when I transited through a US airport with a 3 hour wait.
Never had a problem except for one flight out of Lagos where said disposable was confiscated along with a long forgotten book of matches with just one ( probablly unusable ) soggy match inside.
Stange as one of the security supervisors was happily puffing away in a restricted area - perhaps thats where he got his lighters from...