I think authors are just realizing there's no real reason to feel limited to a narrow set of genre rules in their writing. There's no reason a mystery novel can't have fantastic elements in it. Similarly, there's no reason why your epic fantasy series can't have elements of a mystery.
Patrick RothfussElodin looked at me. "What a remarkably honest threat," he said. "Normally they're much more growlish and gristly than that." "Gristly?" I asked, emphasizing the 't.' "Don't you mean grisly?" "Both," he said. "Usually there's a lot of, 'I'll break your knees. I'll break your neck.'" He shrugged. "Makes me think of gristle, like when you're boning a chicken.
Patrick RothfussNo man is brave that has never walked a hundred miles. If you want to know the truth of who you are, walk until not a person knows your name. Travel is the great leveler, the great teacher, bitter as medicine, crueler than mirror-glass. A long stretch of road will teach you more about yourself than a hundred years of quiet introspection.
Patrick RothfussHumor is hard, hard, hard. And if you fail with humor, you don't fail halfway. You drop the ball humor-wise and everyone notices.
Patrick Rothfuss