Has an author explanation ever been given for why Gryphon can't summon his Asgardian battle armor from Twilight in Midgard? I reread Last Transport the other day and saw the part where even Skuld couldn't figure out why he was unable to summon it. Is it just a matter of it being too powerful and convenient of a plot device for him to be able to summon it anytime and anywhere he needs to like he could with the previous versions of his power armor?