Game Mechanics: Backstab Threat

[Rubby]

Problem: Backstab now generates instant aggro.

Background:
Pre-Patch I was in oasis killing crocs with tanks of all varieties. Never pulled threat off them with a backstab.

Post-Patch I get instant aggro when I backstab.

This change was not mentioned on the list of changes. So unsure if it is deliberate or a bug. But with current system I can only backstab once per fight when mob is low on health or I become the tank for the entire fight.

Locations :
Upper Guk Level 17 Rogue with Level 18 Warrior tanking
Oasis Level 17 Rogue with Level 18 Warrior tanking
Oasis Level 17 Rogue with Level 18 Paladin tanking

Paladin was only able to get aggro when blinding.

Only equipment changes from pre patch to post patch was a Polished Granite Tomahawk in offhand upgraded to a serrated bone dirk. Main hand weapon ( Serrated Bone Dirk ) was not changed. Weapon does not proc.