Do you mean the tonneau cover is moving around?
The 2013 should have the new design with the bungee cords attached.
Make sure you read the Tonneau cover instructions in the 2013 manual,
that should help with the moving around.
I have the old style 2011 tonneau cover and the clips that came with it would detach at around 35 mph and I almost lost the cover, but a forum member Bodih designed these great clips that work unbelievable at any speed.