After navigating to a location (either a Saved Location or selecting a POI or point on the map), the blue pin marking the location will remain when viewing any map screen even after exiting the activity. So if you view the weather map, the blue pin will be there. Or if you view the Map activity, the blue pin will be there. Or while viewing the map screen during any activity, the blue pin will still be there.
A soft reset or off/on will clear it, so it seems that Navigation simply forgets to remove the marker after exiting. I don't recall this behavior prior to 19.XX.
