I've never used that type of spreader but could be.
First thought is they were spraying something hot and didn't overlap. If its that cold it would take weeks for the herbicide to show burning in my experience.
Second thought could be that they were spreading fert at an extremely high rate and not overlapping enough.
Regardless.... get me that applicator's name. He is very good and keeping a straight line!!! Needs a foam marker and he might save me a lot of money on overlapping!!!!!