A question for you pipe sellers on eBay

I've been offering pipes on eBay for 10 years.  Over the course of those years, I've had a handful of eBayers "retract" a bid for different reasons.  It has been a rather rare occurrence.  However, this year...ever since eBay took over all payment functions, I've got bidders retracting bids every single week...and often multiple retractions per week.  I don't list a lot of pipes...just several per week.  The retractions are usually on the ones which appear to be getting good bids...then the retraction comes.  It happens so often now, that I'm actually expecting it.  I've gotten 2 retractions in just the last 2 days.  Never seen anything like it...and I'm getting more than a bit suspicious.  

Any other eBay sellers seeing this?