What are you reading?

So, I went into a local eatery after a dentist appointment and started to read my library book while waiting for my food. The server who brought my food saw the book and asked "what are you reading?" It wasn't a novel, but a self-help book on a kind-of-sensitive topic (and one that she seemed to young to be interested in, frankly). So I just gave her a general answer--a self-help book to assist in one particular area of my life. I felt a bit intruded upon, even though I did pull out a book in a public place, so maybe I set myself up for the question. It's like if you're on a bus and pull out a book--you will get the same question.

This question can be a good question, and for book enthusiasts, it's a very important one. We want to know what other people are reading. We get some of our reading picks by asking folks that question. It should be a well-placed question, though. Is there a general etiquette rule about this? Should we ask Peggy Post or dear Prudence?

She also asked me if the book was good, and if I didn't tell her enough details about her first question, what would be the meaning of asking the second?

It's just idle chit-chat, and filler for folks who don't know what else to say, but I thought it was interesting as a social interaction.