Rails 3.1 and after_intialize

gistfile1.rb

class Invoice < ActiveRecord::Base
  belongs_to :sender
  after_initialize :assign_defaults

  def assign_defaults
    if new_record? && sender
      self.fax ||= sender.fax
    end
  end
end

invoice = Sender.first.invoices.new # sender is nil in assign_defaults
invoice.sender # returns sender properly

Same issue if I use default_value_for plugin (https://github.com/boblail/default_value_for works under 3.1). Has the ordering of after_intialize been changed in 3.1?