The Whites remain unbeaten and top of League One following eight victories from their opening 10 league games.
But they struggled against Carlisle at Elland Road and failed to protect their 15-match run of home league wins as they drew 1-1 with Greg Abbott's men.
Grayson admitted: "It was an average performance from us. I don't think we deserved to win the game. We lacked a lot of sharpness and energy.
"It was an okay performance without ever reaching the levels we have achieved in recent weeks. Maybe we had a few tired legs after a busy schedule. Everybody probably expected us just to turn up and win the game. But Carlisle made it difficult for us and we lacked that cutting edge in the final third of the pitch.
"If at the start of the season you had offered me eight wins and two draws from ten games I would have been delighted."