The way etsy has it set up now is it goes by estimated delivery dates. If the item gets delivered before the date they have to wait until the first etimated delivery date to be able to review the item. Even though I get it that it's to stop people from purchasing and reviewing before they have a chance to get the item, it's still annoying because it seems like when it is delivered that should open up the review period.
edited: I may not have answered your question but what I said is still true LOL. In your case it could be that they checked out as a guest as someone else mentioned.
