Rails app with postgresql; query with .take does not keep the order of records

I have a rails 4 application and I recently switched from SQlite to Postgresql. I have the following 3 models;

class User < ActiveRecord::Base
    has_many :user_games
    has_many :games, :through => :user_games
end

class Game < ActiveRecord::Base
    has_many :user_games
    has_many :users, :through => :user_games
end

class UserGame < ActiveRecord::Base
    belongs_to :user
    belongs_to :game
end

with the records:

game
id
1 

userGame
id  user_id   game_id
1      5         1
2      3         1

user
id
1
2

I could do this with sqlite:

game = Game.Find(1)
game.users.take(2).first

which would return User with id 5.

The same code with postgres gives user with id 3.

Why?