That sense of unease prevails and it felt wholly in keeping that despite taking a two-goal lead, despite looking like scoring more, the final whistle was met with Martial slumping to his knees and staring at the turf in contemplation. A sense of relief swirled.
Mourinho had berated Martial seconds before the end, tearing out of his dugout to implore him to track back, while there were cryptic comments from the manager afterwards suggesting the forward - like other young players - has been held back in the past by the "entourage" that surrounds him.
It must also be remembered that Mourinho wanted United to sell Martial in the off-season, having given up on the 22-year-old. The club resisted, fretting that Martial might come back to haunt them in the way Kevin De Bruyne and Mohamed Salah were allowed to leave Chelsea when Mourinho was manager.
Maybe Mourinho is right. Maybe tough love continues to be the correct approach, but there is that nagging sense that if only he continues to allow his team to play to their strengths - the attacking power at his disposal is undoubtedly far greater than the defensive assets - then it might, just, work. Or at least be better.
"It's almost impossible for us to keep a clean sheet even with a phenomenal goalkeeper and to score is really difficult," Mourinho later said.
That summed it up. There is certainly no Cantona confidence.
United now sit nine points behind leaders Liverpool and still look unlikely to be challenging for the title this season. Chelsea could be there for the long haul, though.
Even without Eden Hazard, Maurizio Sarri's team had far too much for Burnley at Turf Moor. Ross Barkley set up goals for Alvaro Morata and Willian, either side of scoring himself, before Ruben Loftus-Cheek added a late fourth.
Chelsea are unbeaten and in second, two points behind Liverpool.
Arsenal had almost forgotten what it felt like to not win, with 11 straight victories in all competitions since mid-August.
The run is over, however, after a 2-2 draw at Crystal Palace, who claimed a point thanks to the second of two successful penalties by Luka Milivojevic.
Granit Xhaka, with a thunderous free kick, and Pierre-Emerick Aubameyang scored in a five-minute span to put Arsenal ahead by the 56th after Milivojevic's first penalty gave Palace the lead in first-half stoppage time.