We recently had new shingles installed and the roofers (licensed) replaced quite a large number of sheathing planks, supposedly any and all that were damaged or cracked . However, several days after the new shingles were installed, we noticed a rather obvious sunken area sort of centered over one area, maybe a 3 foot wide by 7 or 8 row section).
It was not observed until a day after a rainstorm, but this may be coincidental. The shingles are architectural style with a shadow effect, but the sunken appearing area is not attributal to the shadowing.
We have asked the roofers to come and check this and to also seal down some shingles raised on the ends. Meanwhile, wondering if anyone has had a similar experience.