Pool of water in dishwasher

[aroominyork]

We had a new dishwasher delivered and installed by ao.com a few months ago. In the days after running a cycle, a pool of water builds up at the bottom of the D/W. What might cause this, and is it a warranty issue - or might they say it is a plumbing fault and make a call out charge? It is maybe worth mentioning that during the weeks between removing the old D/W and installing the new one, the unconnected pipe dripped so we had it sitting in a bucket.