Worked on fertilizing lawn last week and I'm assuming I didn't get enough coverage in the lighter spots. Let me know if you think it's something else. Should I just go back over the lighter spots with more fertilizer? Don't wanna burn the lawn.
That looks like fertilizer to me. I've done it before. Next time cut your application rate in half and do two passes. Second pass perpendicular to the first like a checkerboard. Will help get more consistent coverage.