Can you post which eBay category it was? When creating an Item Details profile in Auctiva, you can set the Item Condition, and when the profile is applied it will set the item condition dropdown, but you should be able to change it after the profile is applied. It's possible it has something to do with the eBay category, some ebay categories only allow New item conditions.
http://pages.ebay.com/help/sell/item-condition.html