Willow Rosenberg
I might be just like you!
No there should not have been a new slayer called.
Buffy's first death triggered the next slayer, Kendra.
Then Kendra died and Faith was called. That shows that the main slayer line falls on Faith. But since all the slayers have been activated, if any of them dies except Buffy another will be called.
Buffy's death already activated another slayer, that fact that her second death didn't trigger another shows she cannot do it again.
Then please explain what you think the disruption in Season 7 was....I'd love to hear your theory...