Animations could just be locked to 30 and aren't keyed to 30 frames per second... People unlock locked frame rates all the time.
Just saying. The rest of the game running at 60 except for the fatalities might hint at something worse.
Unless we can verify the rest of the world's running at 30 during fatalities? Like, camera movement? In which case you'd get someone, eh ehm, well known on NeoGAF whose named starts with a D... to do something like that.
probably.