Home Improvement Questions? Ask a Handyman for Answers
Hi. This might apply here (at page 10):
So sealed can be OK, but i don't feel happy about it. It would require yearly inspection. Asphalt shingle under UV tend to shrink and that is fine when they are floating but when nailed they can tear at the non mobile nail position (the sealing need to accomodate for that and be very UV resistent itself).
Having global picture would help to see what happened. Some lemon product can shrink abnormally and expose the nail that were under the upper layer.
Closest document would be 2014 Alberta, 2010 Canada.
I did not see hom much of the roof is like you mention. A fix is acceptable for small defect, but otherwise no nail should be visible and the work should be redone at the cost of the contractor or the shingle manufacturer if the shingle shrinked out of spec and showed the nail under the initially well installed ones .