I started going over my downloaded data from my G3X Touch for another issue and noted something strange that I hadn't seen while in the plane. When the plane was not moving (and the wind was calm) the data showed an IAS of between 17 and 18 mph. I wondered if this was related to propwash but when I go to the beginning of the data (when rpm was 0) it showed the same thing. In addition, the IAS does not increase from about 17-18 until the groundspeed comes up (even at increased rpm) which suggests that it is not propwash. I was curious so went back over several other flights and they all show the same thing. I don't geneerally pay attention to IAS while on the ground so I don't know if this is what is displayed on the PFD as well but I would have to assume so. Any thoughts?