Yeah,
The Dallas Stephen Collection is NOT a PEDIGREE. It is a collection of books and in general, really adds no value to the book.
The difference between a pedigree and collection is that the pedigree came from one source (being the original owner or file copy of the publisher or even a warehouse find). What makes them special (to most collectors) is the uniformity in the preservation of the books.
Collections are just like what you and I have, and therefore don't share the uniformity in preservation. Yes, they might be in high grade, but that's because they were BOUGHT in High Grade, just like you just did.
Of course THAT'S a nice book so