Never heard of that before.
Did you clear payment by money order with the seller before bidding?
While most sellers like receiving mo's, since the buyer pays the cost (sellers using Paypal pay a small fee) and there is no chance that a buyer can get a refund from a third party in case of a dispute, some take eBay's advice that they should only accept electronically traceable payments very literally, not realizing that this protects the buyer and not the seller.