ActiveRecord json serialization should not use keys defined in :methods for included associations

I am currently using as_json with something similar to:

def as_json(opts={})

super(:only => [:foo],
  :methods => [:some_method?], 
  :include => { 
    :assoc => { :only => [:bar] }
  }
)

end

When I render my object to json, I notice that some_method? is being rendered in my json hash for the assoc object. The only workaround I have been able to come up with is to pass an empty [] to the :assoc like:

def as_json(opts={})

super(:only => [:foo],
  :methods => [:some_method?], 
  :include => { 
    :assoc => { :only => [:bar], :methods => [] }
  }
)

end

Is that the intended behavior? It does not seem intuitive that the methods declared at the root for the as_json would get inherited by an included association if no methods are defined for the included association. Bug?