When this happens, it means that an earlier bidder has placed a maximum bid amount which is higher than the amount of your maximum bid. When you placed your bid, the system immediately placed another bid on the earlier bidder's behalf, for an amount just high enough (i.e., plus the bid increment) to outbid your maximum bid amount, insuring his position as high bidder. If the maximum bid that you place is high enough to outbid any other bidders, then the system will do the same for you and maintain your position as the current winning bidder.