Is it possible to win an item on Ebay without bidding on or buying the item?

This may sound like a strange question, but I have had three different buyers that recently won my items through Best Offer but claim they never made an offer on the items. I explained that I have the Best Offer option set to automatically accept the first offer over a specified amount, and that they must have submitted an offer that Ebay automatically accepted, therefore causing them to "win" the item. All three people claim that they found my items on their "won/purchased" tab eventhough they never viewed these items. I find it strange that this happened three times to three different buyers within a two week period. The first time this happened was with a new member so I figured he just didn't know what he was doing, so I just ignored it. But the other two people are both Ebay Powersellers that use the Best Offer feature on some of their auctions so I know they are aware of how Best Offer works.