Office building quote help

I just got a job for an office building. They wanted me to do interior of all the the external widows and all the partition glass on the third floor. This building has 2 wings shaped the same way. I will add some pictures to give you some Idea of what is was like. I ended up quoting him $500 for all of it. A little lower than I wanted to but wanted the job. It took me like 12 to 15 hours to do over 2 days. A lot longer than I thought. Now they are talking to me about doing the same for the other 2 floors. This is the first time I have had a job this big. I starting to think I made a mistake with the quote. What do you guys think is that price good or too low?

like $2,000 off

$2,000 off for just the 3rd floor or the whole building?