The molt is probably just a coincidence. They happen everyonce in a while, and I, at least, dont know of an instance where it's changed. The sleeping may be because of the molt, or because he's less stressed and happier with the new bird.
You may want to try and set it, but if he doesn;t like it or you're not confident in your handiwork you should probaly take him to the vet.
Hope he gets better!