AS automatically adjusts the snipe to meet the existing loads in eBay servers. When it observes that the eBay processing times are lagging, it adds several seconds to be sure your bid makes it in time. Otherwise it risks not being received in time by eBay. If AS did not do this, they would receive many more complaints (like the Sunday night crowds), all demanding to know why their bids were not placed.
I would be pleased that AS placed the bid, rather than getting a "not in time" message from eBay. As for the other two last-second bids, you can be sure that these were planned snipes, just like yours, and were in no way responses to your bid. There was not enough time for that.