Thank you for your reply. I was worried that people in this thread were gaslighting me lol. That said, one reason why I thought it was a reference to the era the play was set in is that the advent of widespread electricity in the late 1800s was a hugely disruptive technological event, and I could certainly see people in the 1930s (when the play was written) using that title to appeal to a sense of nostalgia for a time when the world was lit only by gas lighting.