Your Roof is AGING:

Curling is a common phenomenon in some shingles and is not a
defect. It is natural for asphalt to age and asphalt layers to shrink
with time. This shrinkage may result in the slight curling of the
edges of the shingle.

While minor cracks may not be noticeable from the ground, you might spot them while hanging your Christmas lights. Intense heat from the sun often allows protective asphalt oils to deplete, causing minor cracks. Keep in mind that these normal weathering characteristics are not cause for alarm as long as your shingles are still performing their intended purpose of shedding water. Cracks that penetrate through the fiberglass or organic mat should be investigated.

Occasionally, naturally occurring small, circular raised areas
known as blisters may appear on your roof. These pockets may vary in size and be open (exposing the asphalt) or closed. Blisters are often a direct result of underventilated attics or excessive use
of plastic cement. Closed blisters are not a reason for concern as long as your shingles are still performing their intended purpose of shedding water. However, open blisters do mean asphalt is
exposed and immediate attention is required

In moist, humid areas, dark brown or black patches may appear on roofs. These streaks result in a dirty rooftop, often more visible
on lighter-colored shingles. This naturally occurring stain is caused by algae growth and will not affect your shingles' ability to shed water. Algae discoloration should not be confused with moss or tree droppings, which typically produce only localized discoloration.

While not technically a sign of aging, a distortion of shingles known as
buckling can occur months after original application. Lack of adequate attic ventilation can increase the moisture content of the decking material. This may cause expansion and movement of the wood deck which can lead to buckled shingles.