Is $13,500 to replace the roof on a 1,500 sq. ft. one-story ranch a fair price?

I am feeling nervous about getting a new roof because I don't know what to look for in terms of quality or potential issues. I'm working with a contractor who has done several fairly priced and problem-free jobs for me in the past, including rebuilding my pool deck, fixing fence posts, and replacing a door threshold. His company primarily focuses on roofing and painting. I've scheduled two more quotes from other companies before making a final decision, but I already know I'm likely to use this contractor due to past positive experiences. I'm just getting other quotes to be responsible, as this is an important investment and I have zero knowledge about roofing. I appreciate any advice on what to watch for before, during, and after the job, and any red flags. The current roof has a metal panel edge with heating coils to prevent ice dams, which I use during winter, and while I don't love their look, the contractor advised keeping them. I'm relieved it's only one layer of shingles, and the contractor confirmed he would not do shingle over shingle. I previously tried to get a quote from another company but canceled because they were too sales-focused and wanted a long appointment just to discuss options when I already knew I wanted shingles.