I thought the question might make for interesting conversation and an opportunity to learn if there have been Labs who became famous inspite of the "disability" of having a few white hairs on their chest. Since you are figuring percentages, there were three pups in a litter of seven with white on them. That equates to 42.857% of the litter. I was just "lucky" that all of the white spots happened to be on the girls.
You are welcome to your opinion and you may believe there are issues with my breeding stock if you wish. I think I'd rather have a few white hairs on my puppies chests than many other issues that could occur.
However, you have me reconsidering my position. Perhaps I should have bucketed those defective puppies and kept quiet so you folks wouldn't find out that my bitch has thrown puppies with white spots! I guess I didn't realize how serious an issue it was!