Missunderstanding or a bug?

[Spearhead]

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?

[MallowOni]

It certainly sounds like a bug. You can post it on WotC's DotP forums. They have a stickied thread dedicated to these types of questions.

http://community.wizards.com/go/forum/view/75842/134962/M:TG_-_Duels_of_the_Planeswalkers

[Spearhead]

Thanks.

[Jasmine]

It is definitely a bug.