There is nothing in the disclosure which indicates roof repair. They did have a window leak, but it's hard to see how that would have effected the roof. Certainly something to explore further during the inspection process. It could also be shadows from the upper story. Take a look at the last photo on the MLS listing of the back of the house. The roof there not only has the shadow but a ripple appearance -- that could be architectural shingles.
Here's a link to the MLS pubic detail: http://northernarizonamls.rapmls.com/scripts/mgrqispi.dll?AP