"Singular They" Sighting #1

The "singular they" is everywhere. And I predict that within ten to twenty years (if not sooner), it will be acceptable in most grammar books. I'm not going to make a frequent examples of these posts (because they're too many of them), but I will display prominent ones now and then.

I'm slowly getting used to the "singular they." It's already a standard in spoken dialogue, and it's here to stay--like it or not.

This example comes from Amazon.com where I was leaving feedback for a used book transaction. Notice the third question.