When placing a map marker, it starts off with the bottom of the marker at the selected spot, but when you then select a droplet marker to use, it will be centered. This is how it stays even when the marker is saved. But when you refresh the map, the new marker will be show with its bottom in the right spot again.
Hey, this issue has to do with the type of marker you are using - the next version of Maps will be addressing, thanks for reporting!