Definitely too soon to celebrate but it really looks like Man City are on their way to win the league for the 4th time in a row. It's not just about the 2 points advantage (which is not a lot) but about the fact they have potentially easier games left to play than Liverpool/Arsenal and, moreover, they are the most consistent in performance.
Aston Villa won with Arsenal fair and square. It was not due to luck. They were a better team in that match. I can't say the same about Crystal Palace though, Liverpool has managed to create plenty of chances but were out of luck in trying to convert them into goals.
But that's the beauty of football, if not for surprises like that, it would be boring.