You do not need a ladder to know something is wrong. You need to know what you are looking at.
Curling or cupping edges on the field shingles mean the mat underneath has dried out and is losing its grip on the granules. Dark patches where the surface looks bare are granule loss, which is the shingle losing its UV protection. A line of shingles that sits visibly lower than its neighbours suggests the deck beneath has softened. Granules collecting in the gutter or at the bottom of the downspout are the same story from a different angle. And any daylight visible through the roof from inside the attic is not a warning sign — it is a leak that has not rained yet.
