Missunderstanding or a bug?
I just had the following situation:
Opponent cast 'Rise from the Grave' on a 'Massacre Wurm' in my graveyard.
I attacked in my turn with a 'Phyrexian Obliterator' which says: "Whenever a source deals damage to Phyrexian Obliterator, that source's controller sacrifices that many permanents."
My opponent blocked with the Wurm sending both creatures to the graveyard.
But then I had to sacrifice 6 permanents as the Obliterator's ability resolved.
As I see it, I was not the controller of the Wurm the moment the damage was dealt, so my opponent should have had to sac his/her permanents.
Is this some bug or am I getting something wrong the ability of the Obliterator resolves?
If first is true: How and where do I report this?