At this point I am considering calling the city to inspect the
installation and check for leaks. I know he would not be happy about
it, but I am a bit concerned. What should I do?

Yikes! If there's even the slightest possibilty of a leak, get somebody to
inspect it! I think he'd be a lot less happy if an explosion killed you
and/or leveled your house, don'tcha think?