Android 5.0 Cardio Led topic

Hi,
I just updated my phone to Android 5.0
Now I have this weird problem with the red led of the cardio sensor on the rear of the phone, now it turns on wherever on the ui (not only on S Health). Everytime I put my finger or any object to it, it turns on.
The problem is not hardware, and I have no other apps which have access to it (beside S Health and G Fit)
Please help
Thanks