The Hamlet Project

I wonder if it’s really this line that gets Claudius riled up.
He’s watched, theoretically, the action of the villain poisoning the king twice – first in the dumb show and now in the play. But he doesn’t rise until Hamlet starts talking. And this line is as true for the king of Denmark as it is for the character in this play.
Claudius definitely poisons King Hamlet in the garden for, what is effectively, his estate, if a kingship and country might be called an estate. And Hamlet, too, seconds this bit as what Claudius responds to.
He says, “Upon the talk of the poisoning.” Not the poisoning itself, no – but the TALK of the poisoning.
And while Claudius doesn’t say this when he talks about his sin later, I wonder if he’s more responding to Hamlet’s reference to the poisoning than the poisoning itself. Does he react so strangely because it suddenly seems like Hamlet knows? Maybe subconsciously – since he doesn’t mention it again and it is from here that he gets real keen on sending Hamlet to “England.”