Fedex does this to me all the time. In fact it just happened last week. Ordered a box of cigars and their on line site showed delivered, left on front porch. I looked outside front, back and all around the house, no box. Called Fedex customer service they apologized and said they would get a hold of the driver. Next morning I get a call from the driver and he says he left it behind the chair on my front porch. I explained I don't have a chair on my front porch. He said he would retrieve it and make sure I got it that day. In the mean time my neighbor was knocking at my door with the package in hand. Just glad my neighbors don't smoke cigars.
So I'm not surprised it happened just surprised that you didn't get better customer service from Fedex. Whenever they do it to me they bend over back-wards to get it to me the next day.