Nothing new to glean, at least. Just one piece that's there, waiting for the others to fall into place around them. And to see just how affected he is by the fact that Dexter has something concrete, that's an underscore.
"I'll manage."
The flatness is edging on aggressive - not quite there yet, but there's just a hint of it. The shadow of something that threatens. That would certainly go well, were the two of them to turn more directly confrontational.