A mere basic grammar question, which I would be glad to find an answer to:

When I put the TV on I just heard someone say :

" After all I'm a Stevens , aren't I?"
This is plural for the verb but not for the personal pronoun. Is this correct?

Should it maybe have been or could there also be used here: " , am I not?"

Are both forms correct maybe ? Would anyone be willing to aswer this question? Is it spoken and not written language perhaps?