After tossing away precious points by making uncharacteristic slips at Fulham and Everton in their opening four games, United did it again at Old Trafford last Sunday.
The difference was that Dimitar Berbatov was on hand to rescue his side by completing a brilliant headline which, together with the furore over the interpretation given to Sir Alex Ferguson's comments about Fernando Torres, has rather obscured what nearly turned into a nightmare.
Certainly there is such minimal room for error at the moment that such mistakes in the future could prove even more costly.
Fletcher for one understands the errors must be stopped.
"There has to be a concern that we nearly threw another lead away," said the Scotland skipper.
"We have conceded sloppy goals through lapses in concentration in a number of games and were fortunate Dimitar pulled out the third goal to win the game.
"But we have to remember we threw away a fantastic lead.
"It is something we have to try and put to rest if we want to progress in the Premier League."
The bizarre thing is United have looked fairly solid all season.
At Everton they were coasting until stoppage time and even at Fulham, the Red Devils should have secured victory before Brede Hangeland's late header when Nani missed a penalty.
"It has been individual lapses of concentration that have cost us," said Fletcher.
"It is something we have been looking at and it is important we put it right as soon as possible.
"On the whole, our performances have been very good and really, we should be sitting here with maximum points. Unfortunately we are not."
Certainly concentration among United's defenders will need to be at its peak on Sunday as Sir Alex Ferguson will expect the usual aerial pounding from Bolton at the Reebok Stadium.
Unlike Liverpool and Arsenal, Ferguson's side have tended to enjoy themselves against their local rivals, although usually it involves plenty of early struggles.
"A trip to Bolton is always difficult," said Fletcher.
"When Manchester United are in town, the fans get up for it and the players get up for it.
"At Bolton, taking our scalp means a lot. We know what to expect from them."
Given the way he got Burnley to play, there was a theory Owen Coyle would introduce a more cultured approach on his arrival at Bolton last January.
If that is true, the impact is not immediately obvious to Fletcher, who expects Kevin Davies to be in the thick of the action as usual.
"Maybe they are more of a footballing side but they still have that physical threat," he said.
"Owen Coyle is trying to stamp his mark on the team but the personnel is more or less the same.
"When you have two strikers like Kevin Davies and Johan Elmander, who are big and strong and powerful in the air, they are bound to try and get the ball into our penalty box from wide positions as quickly as possible.
"That is their strength and we will have to deal with it."
It is a strength Fletcher is convinced will need to be repelled before United's more flamboyant attacking stars can exert their influence on proceedings.
"Patience is the key," he said. "Sometimes you have to earn the right to play.
"It is important to keep possession because Bolton are not going to give us too much time on the ball.
"Owen Coyle will have them pressing and working hard all over the pitch so we will have to keep our shape and take our chances when they come."