I realized that, when a bleeds ticks, the damage of the tick depends only on the attackpower + mastery when the bleeds was applied, and not the agility+mastery when the bleed ticks.
For ex:
If i apply rake then use trinket pve to increase agi: the bleeds tick the same amount than if i didnt used the trinket
If i used the trinket PVE then i apply rake, all the ticks of rake are increased, even when the buff of trinket is over.
I dont know if its a bug or its supposed to be like that.
That means that dot snapshotting is fixed. It's not a bug, it's as it should be. This is good news, really good news for all dot-reliant classes (assuming the AP and Mastery calculations are correct).