If you click on your pin within one hour of adding it, you can edit your message or delete your pin, and re-do it. Also, if you just type in your zip code, you can zoom in as close as you want to where your house is, and then double-click the spot on the map to add your pin. :)
Aloha kekahi i kekahi.
It's a flying marshmallow, not a roll of toilet paper!