Not everyone gets it right on the first try. Sometimes, we go back and reread our works from years ago with fresh eyes and find mistakes that we missed during rounds of editing.
It’s coming! A writer’s arch nemesis, the dreaded road to editing. Not really, but you get the point. Most writer’s love writing the story, but the thought of reading, rereading, and rereading some more to find all those developmental and grammatical errors is pretty daunting.