Seller Tactics...

You will have to be more spcific Item # would be great.

It can happen! I am sure some sellers do this to mark up the value or create a hot item. On the other hand, it also depends on the product, some people just open a new account just to bid on that particular item So it all depends.

Need more information brother

There were times when I noticed that a particular seller's always ends an auctions a few minutes to auction end time and cancel off all the bids. After many similar incidents, it aroused my suspicion.

After checking on the seller's transaction history for the past 2 weeks, I realised that the seller often did this.

In addition, there are a few bidders who only bid for this particular seller's items.

Thus I now completely boycott this seller.

You should also report the seller to eBay. I caught a seller using reserve bids on his wares to avoid sales through eBay. He'd set the reserve bids so high that nobody could meet them. Then after the auction closed he'd contact the high bidder of record and offer the item privately for a considerable amount more than what was bid. I turned him in to eBay with corroborating evidence and a week later he was no longer selling on eBay.

sometimes it can just be a coincidence - I had one guy bidding on a load of my auctions for stargate dvds but wasn't bidding on any one elses auctions, to anyone this probably looked a bit sus.

wasnt anything to do with me though

I believe it's called "shill bidding" and it's a kind of fraud. As others have said, eBay will not be happy with this.