If this is true, it's the first time Burial has performed in a lengthy period of time, maybe ever. We'll need some more concrete evidence if we are to confirm it was actually the mysterious producer. For now, read the confused tweets that first reported the news. This could be a massive troll, but it's exciting to speculate.
We'll let you know once more information surfaces.
UPDATE: Looks like it must have been Kode9. Still, sounds like it was an amazing experience.