His team are 18 points clear of Moors after a 3-1 win at the Brewery Field, and Gray's emotions were clear at full-time.
He punched the air in front of the travelling fans after seeing Terry Galbraith, David Dowson and Adam Nicholls score the goals to give Quakers a major boost in the hunt for promotion.
Gray said: "It's a great night for the football club and a proud night, to come here and beat the league champions.
"They hadn't been beaten all season and they take some beating, believe me, because they're a top team.
"We didn't have a team six months ago and now we're 18 points clear of the champions.
"Nobody wins the league in February but we're in a position to really challenge Spennymoor for the title.
"It was crucial not to get beaten, but to come out with this result, and that second-half performance, makes it a great night.
"But it's just another game and it's only three points."
Spennymoor were the better side until Galbraith equalised Gavin Cogdon's penalty, and manager Jason Ainsley admitted his side's failure to build on their 1-0 lead was costly.
"The disappointing thing is that we didn't kill the game off because Darlington couldn't get out of their own half," he said.
"We were superb in the first half, we got into great areas and knocked the ball about well.
"We got the penalty at the right time, but to be fair to Darlington they were the better side in the second half.
"All credit to them, they've turned us over and my lads know that we didn't compete in the second half.
"I'm disappointed, but to lose one game by February is good going and if we carry on that run we will win the league.
"The momentum is still with us and if we win our games in hand we'll go above them."
Quakers were backed by over half of the 2,400 crowd, the largest Northern League attendance since the 1950s.
Gray added: "The Darlington fans played their part. They kept the team going and it was a fantastic night for Northern League football."