I suppose that you mean when you set a player to play the whole match and he misses some seconds, then he has played 48 minutes. If the player plays the whole match then it appears +48, isn´t it?
That's it. The training display on "manage my team" rounds up. So if your guy played 47 minutes and 31 seconds, he will show as 48 minutes. If he played exactly 48 minutes, he will show as 48+.
Run of the Mill Canadian Manager