The Lions dominated much of the game but were beaten by Ed Upson's late goal.
Lomas said: "We only have ourselves to blame, we had five decent chances and we have to take them.
"It was a typical first game of the season where no one really want to put their foot on the ball.
"But once you don't take your chances and the longer the game goes on you leave yourself open to the sucker punch, and that is what happened.
"From our point of view an unopposed shot on the edge of the area is not good enough.
"I thought it should have been 0-0, but if you don't take your chances then they come back to haunt you."