Home Game Rand Ruling Question

[Mithrandir]

In a 6 handed game the other night with all 6 people still in, I went all in before the flop. I had a king/deuece of clubs. 2 People called.
The flop was 2 clubs and an irrelevant card. The other 2 people checked.
The turn was a King, both checked again.
The river was a 3rd club on the board. One person bet, the other folded.
So I said what do you have? The guy who bet said, I've got Kings. I then said I've got Kings... I paused, but I've also got a deuce of clubs. Showing the King high club flush.
The guy who lost the hand then got mad because I didn't call the flush immediately. He thought he had split the pot.
He had thought that the pot should be split, because I said I had Kings, so therefore I have Kings. And not a flush.
I was always under the impression that the cards speak for themselves.
Granted, it could be viewed partly as a dick move on my part for not saying I had the flush right away. However, you can't exactly ignore the cards.

Can I get some feedback on this?

I mean, in a casino a dealer is having you place your cards on the table and then the best hand showing wins.

Could this be simply a house rule people use?

Any feedback is great.