The Slovenia international fired a stoppage-time winner after the Tigers had twice come from behind against Watford on Saturday to extend their unbeaten league run to eight matches.
The three points also ensured the Tigers remain seventh in the npower Championship table and left Koren delighted.
Koren told the club's official website: "In the first three or four games of the season we didn't pick up the points that we should have. But we then started to play better and I think in the last three games we have performed really well.
"Hopefully we can carry on with that and score more goals. Whenever you win a game you are really pleased, but we were really pleased that we managed to get the third goal on Saturday.
"The confidence among the lads is going up game by game and that can only be a good thing. We have such a young squad and that was a massive three points for us. We can build on that now."