Very strange. Maybe it has something to do with your "Thumbnails" setting on "Modify Account" under "My Snipes" tab?
Also, maybe this will help. It's from AS' faq:
Why does the picture not show up when the auction has a photo? (or)
Why is the picture on my Snipe page different than the picture on eBay?
The reason it’s not 100% accurate is because there is no easy way of getting the perfect picture from the auction, since the picture sizes vary so greatly.