This actually happened a week ago, but I'm about to be faced with the same dilemmia of using my cell phone while watching a movie in the dark abyss of a dollar theatre.
Probably you as the reader and fellow champion of law abiding behavior scowled and rolled your eyes over that last comment. Who does that?! you thought unwilling to read further and unable not to quit. I do that just as you most likely check a text when watching a semi-interesting movie in the darkened comfort of your home entertainment center.
But you are right about one thing
it was wrong. So wrong, in fact, that a movie steward a.k.a. Hater of FUN instructed me to turn of my phone. I immediately jumped and threw my hand toward her face, for all I knew the Shadow Man from the Disney movie had somehow found my unaware.
And before I could comment on the fact that there were exactly two people in the theatre, my companion and I, the moviemonger manager had disappeared...into the SHADOWS.
So I'm going back tomorrow and if I am one of two people in the theatre I will pull my phone out and use the flashlight as a warning to the staff.