I think this is not a work made for hire because it was done on contract rather than as an employee. From PubLaw (http://www.publaw.com/work2.html)

"But if the creator of the work is not an employee, but instead a freelancer, than the "work made for hire" requirements of the independent contractor prong must be satisfied. This means that the work must be specially ordered or commissioned by the publisher, the work must fall into one of the nine enumerated categories of work, and there must be a signed writing between the parties where they agree that the work will be considered a "work made for hire."