[Zeke]

Lacquer thinner or acetone for sure on that little bit. When I paint and get a little on the concrete walks (which I cover and try not too, but there's always the ignoramous that walks across your cloth taking the apint to the uncovered areas), I use a little thinner, the brush I mentioned and then I sort of do a spin on the ball of my foot in my sneakers on top of the spot. You would never find the spotted areas after that trick. Sounds stupid until you try it.

Be careful with a pressure washer. At high pressures, they can make marks in concrete (stripes) that will be there forever, especially fresh uncured concrete. I'm talking less than 2 months old.