Technically, it ain't 'prime' rib. It's a ribeye roast. Only USDA Prime beef can be called 'prime' anything.
Funny thing, our family bought and prepared the same exact thing! It was great, for a select grade of beef. We oven roasted ours, since our smoker is dead. I didn't get a new smoker for Christmas, so it's shopping time.
I coated our ribeye roast with oil, salt and fresh cracked black pepper. We roasted it at 350 until internal temp hit 118. We then tented it under some aluminum foil until she hit 135. Yeah, that's how much carry over heat there is in a roast this size. Taking it to 140 is way too high, I think. At 135, it was perfect medium-rare.
Our ribeye roast dinner was fantastic, and so were the leftovers. No doubt your meal was fantastic, too. My sister's family made the same roast, too.