One thing you might consider especially if your weight distribution hitch has friction sway control built in and is dependent upon spring bar force. Could be the return trip is different than at departure. Did you burn all the firewood loaded in the bed of the truck? Did you drink all the beer and eat all the food? Was it cold and you burned through a bunch of propane? Could be you are towing back considerably lighter then when you set up your hitch. Less weight on the tongue and in the bed of the truck will raise your hitch and change the bar angle. This will result in unloading of the bars and possible diminish the effectiveness of your sway control.
One more thing to think about.
