Need to watch the ep again, but wasn't it the fact that the Alpha was with the ten that pressed the panic button? Dean and Ketch were only anticipating ten ordinary vamps, plus I think their confidence was supposed to indicate their reckless bloodlust - speaking of which, I felt there was a strong nod back to Bloodlust in the Ketch/Dean bond. Dean was drawn to Ketch in the same way as he was initially to Gordon, because he claimed a kinship and understanding of Dean's dark side but, as in Bloodlust, Dean drew the line at wanton sadism. I think he instinctively saw Lenore in the vampire Ketch was beating up, and he may have been right to. It was interesting that the vamp who offered her the glass of blood* made a point of saying it was human, like that would be a treat for her. It made me suspect that her nest may have been cow blood drinkers until hunters wiped them out. So, I do think the grey areas of monster-is-as-monster-does may become an issue at some point.

*I think we're going to have to hand wave the fresh blood issue. Drinking blood out of wine goblets has become a common trope of vampire fiction.

Incidentally, it's not the first of Beren's episodes to allude heavily to Bloodlust. Seems it's an old favourite of his.