He could be adjusting and if he was handle and sex in the mean time it could cause a slight delay.
Usually I always recommend to wait a week and NO handling before proceeding to feed their new animal, another important thing is feeding the same type prey previously offered.
After that it's really about how you offer as well, I would recommend thawing at room temps near the enclosure (this is called scenting) to entice the snake to eat, once thawed warm the prey up with a hair dryer, now when it comes to the way you hold the prey it can play a part as well, young animals seems to be a lot more interested when the prey is held from behind the neck and move around like a live mouse/rat would move versus dangling by the tail, sometime that little trick make all the difference in the being willing to switch or eat F/T.