User blog:Kajune/Why did Lilith want to kill Sam?

I've been wondering...

Is it a continuity error, or was there a proper reason why Lilith wanted to kill Sam up until her final appearance?

It was mentioned that Lilith and Sam were competitors for the leadership of the demon army, so Lilith needed Sam dead. This was season 3. She had another reason to kill him during season 4, which was as compensation for her own death during the Apocalypse.

So...Lilith tried to kill Sam during season 3, unaware it would botch the Apocalypse and Lucifer's plan for freedom, right? Am I right to be sensing a continuity error?