Ok...interesting. From what I understand, the Health app logs steps from both the watch and the
Tap on sources, at the very bottom is the list of devices that feed data to Health.
You may have two devices listed, your watch and your phone, and tapping on either
of them, then Steps, it will show the number of steps and the time of the steps...tap that entry
and you'll get even more details about that step entry.
Looking at this data, you should be able to verify if those Ghost Steps are coming from your watch,
or maybe even more probable, your phone...
I look forward to what you find out.