Wade, here's part of an email George sent me one time. It's really dealing with orders so I'm not sure it applies, but I'm posting in case it's of use to you or anyone else:
My system stores your orders until you place them or cancel them, so you can always start an order and go back to it later. I do periodically cancel orders that are more than 6 months old if they are with an unregistered user. Since you are registered, your orders will remain available indefinitely.