Hot Rods New Paint advice

Just got my old truck painted by a friend of a friend. We've all heard the story and you definitely get what you pay for! Lesson learned...Paint is a flattened single stage urethane. Painter did a good job laying the paint, but! There are a few spots that have what looks like dirt!! My question is. Paint is a little too shiny for me still. Can I fix the spots with dirt and shoot over with a flat clear? Or will i have to reshoot the entire truck? Thanks for any tips/help