a lil rough in high gear???

[CB1]

i have an 05 fx4 6.0 with 95000mi auto trans this is my first powerstroke (former dodge guy) anyway when i jump in my truck an drive it its fine an smooth but when i get the trans into a high gear 55 to 65mph it kinda gets into a "junping mode" an kinda bounces a lil bit it only does this for a lil bit until the truck gets good an warm and runs through the gears a couple times does anyone else have this problem? is it normal? or do i have something wrong?