Just days after beating Dunfermline to move top of the Irn-Bru First Division, the Ton failed to take advantage of Partick Thistle's inactivity as they kicked off 2013 with a shock 3-0 home defeat to the bottom-of-the-table Sons.
Moore said: "Football is a funny game. We had a double programme on Wednesday from the game before Christmas and I said in the programme that the Partick Thistle game and Dunfermline game didn't worry me, Dumbarton was the game that worried me.
"I am disappointed for the fans that turned up. Every time we get a bit ahead of ourselves we let ourselves down. I didn't see it coming."
Next up for the Ton is tomorrow's clash against relegation battlers Cowdenbeath.
And Moore knows his side must improve at both ends of the park if they are to recapture the form that shot them into pole position in the title race.
He said: "From the first minute to the last we didn't compete enough. We created three or four good chances in the first half and Peter Weatherson has got two. If he buries them we are 2-0 up and it is a different game.
"They then went up the park from a breakaway and scored. A lot of teams are going to do that here, they are going to get behind the ball.
"What disappoints me most is that we have lost three goals, and no disrespect to Dumbarton, to a team that are bottom of the league.
"We lost three goals to the two teams at the top of the league and we then lost three at home to a team at the bottom.
"We said at the start of the season that our home record has got to get better. The fans turned up and we have disappointed them yet again.
"It is the same team, the same players and the same formation that has run amok in the last 13 to 14 games."