While it would be great to think that this is a short term rise, Utd have actually got the most points over the last 5 games, last 10 games, last 15 games, last 25 games, and last 30 games. The only stretch that they don't have the most points over is 20 games when they are 1 point behind City's total. Now, they may not have always played well in those games, and have certainly benefited from some luck and some generous referee calls, but points on the board are points on the board.
However, as has been mentioned several times, this is a very odd season. Utd are top with 36 points after 17 games and in the last 10 years that points total would have only been good enough for 1st place in one other season (2013/14). In two of those years they wouldn't have been in the top 3 places, and in 7 of those years they would have been at least 6 points off the lead, and for the last 3 years they would have been at least 13 points behind the leaders.
So this isn't Utd catching up with City and Liverpool as some pundits have been saying, this is City and Liverpool essentially slamming on the brakes to let them overtake them.
Lots of games still to go and there are no trophies awarded for being top after 17 games.