On eBay, the bids are listed from highest to lowest, not by time of bid. The highest bid will appear at the top of the list at all times. If billcin1's proxy was higher than succeeding bids, they will slide below his on the list.

So, although most of the other bids made yesterday were made after billcin1's, his proxy was higher and, therefore, his bid stayed at the top of the list. Evidently, all of Sheldon's bids were lower than billcin's proxy.