The thought never entered my mind. I agree that Paul probably had this in mind.
Words get their meaning from context.
The Jews used the Shema every day in their daily prayers. To try to divorce the divine title from these words would be near schizophrenic for the Jew. I highlight this since Paul utilizes Israel's history as major support for one of his major points. In other words, Paul comes at the theme from within and characterized by a Jewish theological framework. He's thinking Jewishly.