When Jamie Mackie put QPR ahead at Old Trafford yesterday, it was the 13th time this season United had gone behind.
The reply, through Jonny Evans, Darren Fletcher and Javier Hernandez, ensured it was the ninth occasion when United have been able to salvage the situation and claim victory.
“We should be concerned. It is a bad habit,” said Lindegaard.
“We have to look at it. I just asked one of my team-mates afterwards, ‘what would have happened if we hadn’t conceded a goal?’ It was like a wake-up call.”