Yes, [ she confirms with a nod — of course, later on she will know of Bran, and tell about him to Diana, but for now this is all she can share. ]

It's rare. Not impossible, but rare. Ser Davos used to be a smuggler, but was knighted by Lord Stannis, and I've heard that one of Daenerys' closest friends and advisers was a former slave. [ but the fact that she can only name two examples is probably very telling. ]