Recently I replaced my roof and I have a narrow area that required laying shingles. In this area the contractors nailed down the shingles and covered the nail heads with a black colored substance. I am worried whether nails would eventually get rusted and that I may get a leak. Also in here the flashing is underneath the shingles, which would cause the rain water to go underneath the shingles, which is again isn’t very good.
Was there a better way my contractor could have done this job? If I call him back to fix it, what should I be asking him to do?
Picture can be viewed here: https://drive.google.com/file/d/0B0sqTWrQBwg4c0ViVi16Qm1JdlBUeWc4ck5hNy1xV0RlQzJz/view?usp=sharing