I remember back when this happend to ravenmimura. Then it happened to me a few months ago when I needed a pair of boots in time for a photo shoot and UPS screwed that up. It seems to be a consistant habit of UPS to not even try to see if you're home before leaving an attempted delivery notice. I mean maybe they just knock once lightly and then take off. From what I was told a few years ago they get to go home after they finish their route whether they finish it in 6 hours or 8. So it's in their best interest not to ring your doorbell and wait for you to answer.
Whatever the reason, UPS stopped by WHILE I WAS HOME and left me an attempted deliver notice...again!!!