Could be a drainage issue as well - is there a noticeable amount of water left in the bottom when you open the door? My dishwasher did this about a year ago and it ended up being a blockage in the drainage line and thankfully not a blown pump - which is what the service tech my wife called said it was.
When troubleshooting appliances, start with the simplest, least expensive possibility first and work your way up. There are a lot of do-it-yourself guides for this kind of thing on the internet;
here is one of them.