I was recently on an airplane reading Why I Am Not a Christian and Other Essays on Religion, by Bertrand Russell. I was concerned about how other passengers might feel if they saw me reading a book with such a title. So I tried to make sure no one could see exactly what I was reading. Is there a single word or short phrase that describes my hiding something out of concern for offending others? I haven't been able to come up with a word or short phrase that really works.
careful not to cause embarrassment or attract too much attention, especially by keeping something secret:
The family made discreet enquiries about his background.
They are very good assistants, very discreet - they wouldn't go talking to the press.
I would suggest a phrase solicitous discretion
solicitous: characterized by or showing interest or concern:
she was always solicitous about the welfare of her students
a solicitous inquiry
discretion: the quality of behaving or speaking in such a way as to avoid causing offense or revealing private information:
she knew she could rely on his discretion
Oxford Dictionaries Online
You may have just been self-conscious then.
self-conscious adjective nervous or uncomfortable because you are worried about what people think about you or your actions:
He looked uncomfortable, like a self-conscious adolescent.
I always feel a bit self-conscious in a hat.
Stop staring - you make me self-conscious.
You were cautious not to set of peoples sensibilities. One might even say you put on the kid-gloves to handle the situation with potential hostilities in a confined space. You were doing this out of prudence. It was a tactful move on your part.
cautious ADJECTIVE 1 (Of a person) careful to avoid potential problems or dangers:
kid gloves, phrase: handle (or treat) someone/thing with kid gloves: Deal with someone or something very carefully or tactfully
prudence NOUN [MASS NOUN] The quality of being prudent; cautiousness
tactful ADJECTIVE Having or showing skill and sensitivity in dealing with others or with difficult issues