yes. IANAL but... copyright law in the US is such that, in essence, everything is copyrighted (to some degree) the moment it is created unless you explicitly state otherwise.
When dealing with anything legally distributed / created in the US there are many questions, but "is it copywritten" should be one of the last ones, because the answer is always YES.
When dealing with anything legally distributed / created in the US there are many questions, but "is it copywritten" should be one of the last ones, because the answer is always YES.