I am currently remodeling a house that was built in the 60s. I been working with different contractors here and there for various jobs. I'm finding myself frustrated alot by alot of the small details they miss. For instance, I recently had impact windows installed by one contractor then hired another contractor shortly after to install windows sills. I noticed a pretty decent sized gap in between the sill and windows, so I asked the sill contractor to fix the gap as opposed to filling it with caulk as he was planning to. He then tells me well the windows are seated at a slight angle. So I broke out my ruler and discovered that indeed they were. What should be doing in situations like this, do I just let it go, or do I push back? It is an older house, but the engineer in me wants everything to be done with the minor details in mind. I get very stressed and annoyed when I find stuff like this. I know at the end of the day this is a business and a window installed at a 3 degree angle won't stop me from finding renters, but anything I typically work on I like to have it be of great quality as well, especially if my name is attached. Am I digging to deep or am I right to break out ruler and leveler on every contractor that comes through?

Also how should one go about getting things corrected after the work has been done and paid for?