I was very surprised the first time this happened to me a couple years ago. I was surprised because I remember reading an AS tutorial that discussed choosing times appropriate to the ebay traffic patterns. It said that longer lead times would be needed on Sunday and/or auctions ending on the hour, for examples, or one would risk having a bid not make it through before the auction close. So, I was really shocked when AS further padded the lead time. The first time it happened I ended up paying much more for an item because someone got in a subsequent manual bid after their first one was too low to beat my AS snipe. I have since lost a few items as a result of others getting more than one bid in after AS placed my snipe. Yes, I mean the same bidder placing a second bid (or a third bid in one case) when their first wasn't high enough to beat the bid AS placed for me well in advance. I've had several AS snipes reach ebay more than 40 seconds prior to the end of the auction. That is no help at all.
As with several snipers above, I would much prefer to have the bid not go through than to have the bid placed far in advance. That way, if it doesn't go through it is due to my incorrect lead time choice rather than AS's faulty time gauge. At least I can control and learn to adapt the former.