If you think anyone at Manchester United would be allowed to get away with an attitude like that then you are extraordinarily naive. There is no issue with his desire, his match fitness will improve as he gets more of those thingies, erm, matches, that's it.
I really do hope that's the case. He's had 8 starts so far this season and so by this point, after a week's training and rest, I would personally be hoping to see some signs of improvement in his match fitness. There were none tonight. Same old Anderson.