In supernatural season 12 episode 8, LOTUS, Castiel comes to Sam and Dean and tells them there's a child of an angel and a human coming.

And Dean gets nervous and looks uncomfortably to Cas, but before he says anything Castiel continues to speak.

He continues to tell them it's more powerful then regular and Sam answers with its Lucifer that made the baby.

Then Dean looks less panicked.

Can we talk about this?

I mean why would Dean panic about an angel and human baby and look directly to Cas in his panic first?