What's in a Preposition?

First pointed out through the astute observations of Andy Porter, writing in the Vintage Paperback Yahoo! Group, comes the baffling mystery of the substituted preposition. 

Printed first as Ace D-44, and reprinted as Ace D-468, the cover incorrectly displays the title: Sentinels of Space, by Frank Russell. The Title page displays the correct title: Sentinels FROM Space, as seen below.

Obviously in an effort to save money by using the same cover layout, Ace changed the name only on the spine of the book when they reprinted it.

The spine of D-44 reproduced the error from the cover. At least that one was consistent.