Quasi-Automotive Puzzler

I was driving down a two-lane road this evening that had obviously had its double-yellow line re-sprayed within the last week or so. I noticed that I could tell which way the paint truck had been going while spraying. How?

If the sprayer was moving over a small depression in the road, one edge of the depression might get a lot of paint and the other might not get any.

The direction of spatter and drips.

Nope, much more obvious (answer tomorrowbelow).

Yellow tire marks after passing the truck due to lane change?

Ding, ding, ding, we have a winner! Yep, those low-lifes that can’t take an extra 2 minutes for the truck to finish a stretch of road.