_validators works on ActiveRecord::Base instead of individual models

When I have

# app/model/ingredients.rb
class Ingredient < ActiveRecord::Base
  attr_accessible :product, :name, :quantity
  belongs_to :product
  validates :product_id, :presence => true
end

# app/model/products.rb
class Product < ActiveRecord::Base
  attr_accessible :name
  has_many :ingredients
  validates :name, :presence => true
  accepts_nested_attributes_for :ingredients, :allow_destroy => true
end

And in Rails console I do this

$ rails c
Loading development environment (Rails 3.0.0.beta4)
ruby-1.9.2-rc2 > Ingredient.validators_on(:name)
 => [] 
ruby-1.9.2-rc2 > p = Product.new
 => #<Product id: nil, name: nil, created_at: nil, updated_at: nil>
ruby-1.9.2-rc2 > p.class == Product
 => true 
ruby-1.9.2-rc2 > p.ingredients.build
 => #<Ingredient id: nil, product_id: nil, name: nil, created_at: nil, updated_at: nil> 
ruby-1.9.2-rc2 > p.ingredients[0]   
 => #<Ingredient id: nil, product_id: nil, name: nil, created_at: nil, updated_at: nil> 
ruby-1.9.2-rc2 > p.ingredients[0].class
 => Ingredient(id: integer, product_id: integer, name: string, created_at: datetime, updated_at: datetime) 
ruby-1.9.2-rc2 > p.ingredients[0].class == Ingredient
 => true 
ruby-1.9.2-rc2 > p.ingredients[0].class.validators_on(:name)
 => [#<ActiveModel::Validations::PresenceValidator:0x00000002831920 @attributes=[:name], @options={}>]
ruby-1.9.2-rc2 > Ingredient.validators_on(:name)
 => [#<ActiveModel::Validations::PresenceValidator:0x00000002831920 @attributes=[:name], @options={}>]
ruby-1.9.2-rc2 >

I expect the Ingredient.validators_on(:name) to be [] as in the beginning.