If it is spray injury--you should be able to find subtle "tells". It should be worse nearest where you were standing. and less injury on the back side of the tree or anyplace that is difficult to access. Gaps in coverage should be visible. Bacterial spot usually develops more slowly and the new spots have a water soaked ring around the spot. Bacteria need a previous infection to start from. And the bactieria need warm moist rainy misty weather. Wish I could help more.