I believe most dishwashers have a little bit of water left in the bottom after a wash cycle to keep the bottom seal moist so it don't dry out. Not completely sure about that though wait until you hear other replies.
Do you notice that the soap is not being used up completely like it's just running down the inside of the door? Mine did that a little, and told my wife (new house to us) that I probably needed to loop up the drain hose. I checked and it was okay. A couple weeks later it stopped using the soap all the way. I ended up having to pull the pump screen out and clean it. It was clogged with all kinds of greasy cheesy looking crud. Works great now.