Only once did I encounter significant trailer sway. My rig is set up well and I rarely even feel push from semi’s. I was in Utah and while slowly passing a semi on a gentle curve, there was a almost insignificant drop off from the road to the shoulder due to construction. The trailer wheels crossed over the slight drop just as I hit the bow wave from the semi and possible got hit by a gust of wind (had numerous gusts that day). The trailer did one large pendulum swing and then stabilized when the truck anti-sway kicked in. It happened so quick that I didn’t even have time to think about it before it was over.
Yes trailer sway can occur due to many unforeseen circumstances.
