When you purchase your mugs, there is a sign that says they are for "this visit" (in simple terms). Now, there may be flames for the rest of my response - sorry. You will notice during your next trip that there will be many people that have "older" mugs with them. It seems to be a rare situation that a CM will stop you from refilling one of those mugs. That said - you should be prepared for this if you choose to bring your mugs back. They are not resort specific.