Is It Ethical Or Wrong To Read Books In A Bookstore Without Paying ?

At Barnes & Nobles bookstore there are couches all over the store and one can go to the in-store Starbucks and sit at a table and read books all day.

I have done this without paying for the book that I read while sitting on one of the stores couches.

Is this wrong to do ?

After all, it seems like they encourage you to stay and " hang-out " with them, thus, all the couches there.

What is your thoughts on this..