This is the sort of thing only a SW geek would notice after a gazillion viewings of the saga. It's A/P fanon that our favorite doomed couple likes to cuddle or sleep in each other's arms or whatever. So when we don't see them sleeping that way in ROTS, many fans thought, "Well, that's the squeaky clean SW universe for you." (Of course, many other fans thought, "Whoa, a couple in the same bed! This is the equivalent of full-frontal nudity!")
In any case, I think there are simple explanations for the way A/P are sleeping in that particular scene. From a symbolic standpoint, I think it shows the two are about to be put on separate paths especially since it's the scene where Anakin has his fateful nightmare that sets the tragedy into motion. Anakin is isolated by his fears and Padme can't quite reach him. But upon observation of AOTC, there's perhaps a more practical explanation. Notice how Padme is sleeping in the scene where the kohluns are creeping on her…on her right side. And, later on, notice how Anakin is sleeping when he has his nightmare about Shmi. Flat on his back. In ROTS, they are sleeping the exact same way…Padme on her right side and Anakin flat on his back. Cuddlebunnies aside, people do have their preferences on how they like to sleep. It just amazes me they remembered that three years after filming AOTC, even if it was purely an unconscious memory.
In any case, I think there are simple explanations for the way A/P are sleeping in that particular scene. From a symbolic standpoint, I think it shows the two are about to be put on separate paths especially since it's the scene where Anakin has his fateful nightmare that sets the tragedy into motion. Anakin is isolated by his fears and Padme can't quite reach him. But upon observation of AOTC, there's perhaps a more practical explanation. Notice how Padme is sleeping in the scene where the kohluns are creeping on her…on her right side. And, later on, notice how Anakin is sleeping when he has his nightmare about Shmi. Flat on his back. In ROTS, they are sleeping the exact same way…Padme on her right side and Anakin flat on his back. Cuddlebunnies aside, people do have their preferences on how they like to sleep. It just amazes me they remembered that three years after filming AOTC, even if it was purely an unconscious memory.