I have a pb copy of The Fiery Cross by Diana Gabaldon, isbn 0-385-33676-4.  I got it a couple of months ago, and am finally getting around to posting it when I realize/remember there is a small pen scribble on the cover of the book right over the authors name. 

I looked at the help docs, and I know writing is not allowed, but this is on the cover, not on text pages.   It is otherwise in very good condition.  I was really excited to get the book so when I received it I didn't really pay attention or mark it RWAP. 

Is it postable, or should I just offer it with an order?

It's postable.  The Help Center comment about writing applies to the text pages (as it says in the HC) and nothing is said about writing in the section on the cover's condition.  Some Used Book Stores even write the prices directly on the cover with marker; these books are still postable, so a small scribble over the author's name should be no different.  If a Requester is aiming for collectable copies it would be up to them to employ Requester Conditions to that effect.  Post away, you shouldn't have any trouble.

I agree, sounds perfectly postable to me.

Spiffy.  Thanks!