Moordog,
I agree with Stuart, if the dealer used the proper procedure at the showdown, that would not have happened. You mentioned that the players hesitated at the showdown before showing their hands. There is a proper order of showdown that should be followed but, it really doesn't make a difference in this case. The error by the dealer was not asking for the cards (so they could be mucked), before pushing the pot to the other player. Whenever I am dealing and two players remain at the showdow, I will ask to see the cards..."okay , lets see them."
when the first player turns his cards face up on the table, I will read the hand and wait for the other player to muck or show a better hand. Until that happens, the dealer should never award the pot. I don't like awarding the pot to a player that verbally conceded but, like Stuart says, by the book, the hand is live until it hits the muck.