Cord is probably the key to finding Adam, and Sam hates it.
Cord is a demon, and he's come to accept that. Cord is a threat to his safety, but like Miczariel, he's found himself trusting him. Ever since he walked into that bar and found neutral ground, despite their disagreement on where angels stand, he's considered Cord an ally of sorts. Not one he knows if he can rely on a fight though, because they haven't been around each other much, but he can talk to them openly within limit. There's something freeing - and creepy - about someone knowing all of your past.
(Which he can live with if they're a demon or angel and it comes with the territory, humans knowing makes him wonder who they've been talking to and if he should have a gun handy.)
But Cord hasn't turned it against him for a moment. He's shown understanding for where he stands, and they've only been at a crossroads in agreement once over Adam. Cord wanting to protect him and knowing Sam's a danger, and Sam knowing he might have to do something that would turn Cord against him. He has to find Adam though, he worries about it, knowing he might have to kill his brother, and that will lose his closeness and respect he's built up with Cord - that the building friendship they have will shatter.
He is thankful, nonetheless, that even if Dean and him have let Adam down in the long run in his view, Adam found someone else willing to take care of him.