Vibration at 40-60mph

So I just replaced my oil, rear differential fluid, rotated my tires and got an alignment yesterday. And I noticed at on the freeway today that at 40-65mp when I let off the gas I get a vibration. I also tested it from a stop light getting onto the freeway, I floored it from a stop to 55mph and let off the gas. Again that same vibration. The best way I could describe it. Is like having cupped tires, problem is my tires are newish and not cupped. I do know my u-joints could use a good greasing. My carrier bearing does have some up and down play when I push/pull my drive shaft. Does anyone have any other thoughts? It looks like my carrier bearing is original to my 2011 btw

 

Vibration when letting go off the gas is a strong sign of warped rotors.
You don't always need to feel it while breaking for it to be the case.
Also super easy to swap so worth a try.

 

I wish that were the case, I went and replaced all 4 sets of brakes less than 5k ago cause they were all due for pads so I figured rotors id do the rotors as well.

 

Take it back to the alignment shop...or a better one.

 

Check for signs of fallen weights from the wheels.
That happened to mine during a rotation 2 years ago .

 

wouldn’t you be able to tell though at all speeds?
I did find my carrier bearing is beginning to fail so im assuming that’s part of the problem and my u joints were in need of some greasing. As I haven’t greased them since I got the truck two years ago.
Just greasing has made a noticeable change.