This has happened a few times and figure I should submit a bug report for it. I recently requested the book "Savage Awakening 7", and this is a fairly new book, a bit over a week old, so I was not too surprised when there were no results. However, ABR still grabbed some other book with a totally different title and started downloading it instead.
I am not sure how best to combat this, other than to make the matching more aggressive, which has its own problems i'm sure. Maybe its worth making name matching more aggressive in the few weeks after release of a book?
Possibly similar to this issue: #112
Though that one might be a bit different with it being an issue with short names.