Rashford, 25, came off the bench to score the winner at Molineux on Saturday after manager Erik ten Hag said he had been dropped for unspecified "internal disciplinary" reasons.
He had been expected to lead United's forward line after scoring two goals in two games since returning to club action following his involvement at the World Cup with England.
However, speaking after his match-winning performance, Rashford revealed the reasons why he faced disciplinary action from his manager.
"Obviously it's team rules. I made a mistake," he told BT Sport after the game. "That can happen. I'm obviously disappointed not to play but I understand the decision and I'm happy we managed to win anyway.
"We draw a line under it and move on. I was a little bit late for a meeting. I overslept but it can happen."
Ten Hag has shown his readiness to make big decisions with star players already this season, with the former Ajax manager dropping Cristiano Ronaldo from the squad for the league game at Chelsea after the Portugal captain refused to play as a substitute against Tottenham.
Argentine forward Alejandro Garnacho was overlooked for games on the preseason tour of Australia after angering Ten Hag with his time-keeping, so the manager's decision to drop Rashford is in keeping with his determination to ensure that his players adhere to his strict rules.
United recently triggered a 12-month option to extend Rashford's Old Trafford contract with his previous deal being set to expire at the end of this season.
Rashford has enjoyed a fine run of form this season and said the team are ready to improve on last season's disappointing campaign.
"I think I'm in a good place," he added. "I'm just pleased with the way we're progressing. In the past we could have easily lost that game or definitely drawn it. They put a lot of pressure on us but we stood up to it well and David [de Gea] made a massive save late on.
"It's going to be tough like any other season but we've got to push ourselves and try to get as high up the table as possible. A lot of the teams are going well this year and being very consistent. We have to be on top of our game to try to go one step further."
United teammate Casemiro praised Rashford for his performance and said he could become one of the best players in the world.
"I'm gonna be very honest with you. I was really surprised with the player Rashford is," he told ESPN Brasil after the game. "In my opinion, especially knowing the player off the pitch, I can tell you that if he's doing well, he can be one of the top five players in the world.
"He has an incredible way of hiting the ball, he's got strengh, he's quick, is very clever playing. He was one of the players that really surprised me. Of course when you play in a different league you already know the player, but when you're in the same club every day.
"What a spectacular player. I'm enjoying so much playing with him. He gives us a lot of energy. I'm delighted to play with him. And I' sure if he stays like this, with the conditions he has, he can easily be a top five player because he's exceptional."