[danhanan]

Not trying to play devil's advocate here, but from someone who has been at the other end of the spectrum. let me say this. As long as that's as far as it goes - a simiple, polite closing, I wouldn't worry. However, that's how our DDs bmom started out and by the time we smartened up and called an end to it, she was prompting her children who are all older than DD to say things to her such as, "you'll come and live with us someday", and, "dont' call her "K", call her mom, she's mom". Other family members of hers have witnessed her prompting her kids. So, just pay attention and make sure it doesn't start to escalate.
So, chances are it's innocent, but just keep paying attention and don't feel badly for being on your toes.