yes...The Ferrari logo is part of the theme and you need the Copyright/Trademark holder's permission to "use" it. No matter if it was free or for sale.
I've seen enough Cease and Decist orders from Copyright/Trademark owners over the past several months that would make your head spin.
LaCoste was the latest one to chime in. They take this stuff seriously...just because you can download an image from google images or some other plac eon the net, does not give anyone the right to reproduce it...free or premium.