She didn't look happy.
Like I said on another thread (same topic), I've been surprised by an impromptu back rub from my husband, even co-workers and friends. If televised, my reaction may not look happy, due to surprise, or the "hurts so good" reaction of shrugged shoulders.
Like I said, Merkel did not complain. It is for HER to judge. Not MSNB-See only what they want to.
I saw a picture of how she looked right after the "4 second" back rub and she was smiling and I imagine she laughed--that would be my reaction if the POTUS ever did it to me(oh how I wish!)