Yes, it seems to be very common to have these cancellations, with the item being sold in a side-deal, off-eBay.

If you are seriously interested in an item, it is prudent to send the seller a message. You don't necessarily need to make an offer or attempt to buy off-eBay, but if you don't let the seller know that you are very interested, then you may never hear another word before receiving the dreaded message "eBay Bid Cancellation Notice". Most sellers seem to want their auctions to run their course, but many sellers will be tempted by what looks like a generous offer. Of course, when these sellers do not know the values, then they often lose out by ending the auction early.

eBay = The Wild West. Got to know what you are up against, to have a chance.

Jeff