Using "skip_before_filter" in controller logs me out

I have a controller action that I need to call using AJAX. So I used skip_before_filter to turn off the requirement that I be logged in for that particular call.

That works, but on subsequent requests, I get redirected to the login form. How can I avoid this?

Here's the filter code in the controller:

protect_from_forgery
before_filter :logged_in?
skip_before_filter :logged_in?, :only => [:toggle_waiver]

Here's the controller action:

  def toggle_waiver
    @household = Household.find(params[:household_id])
    @household.update_attributes(:waive_latefee => params[:bool])
    render :nothing => true
  end

The logged_in? method is simply a home grown one:

def self.authenticate(username, password)
  user = find_by_username(username)
  if user && user.password_hash == BCrypt::Engine.hash_secret(password, user.password_salt)
    user
  else
    nil
  end
end

Is there a better way to be doing this? (I'm using Rails 3... don't judge me) :-)