auth.rb

class Auth
  attr_accessible :token
  def authorised?
    token = self.token if token.valid?
    token =|| token.refresh
    token ? true : false
  end
end

profile.rb

class Profile
  def self.fetch
    raise UnauthoriseError, 'Un-Authorised attempt to fetch profile' unless Auth.authorised?
    # continue fetching profile
  end
end

token.rb

class Token
  attr_accessible :token, :expires_in, :refresh_token
  
  def valid?
    # return false if expired, true otherwise
  end
  
  def refresh_token
    # refresh token and expiry
  end
end

@adtaylor, you could even take this further by abstracting all this fetching stuff into a mixin or something. Then all you need to do is set the endpoint for the resource profile and give it the token instance.