Auction ended too soon, is that possible?

[k_littell]

I had a single auction item listed, "item X" then i posted another 2 items a few days later, "Item Y' and "Item Z". All were 1 week auctions. I just checked the My eBay section and Item X was still active but somehow items Y and Z had already sold. I'm happy that they sold, but there were a bunch of people watching Item Z and I feel like money was left on the table. What happened? Thanks in advance....