I had that same problem when I moved into another house and found out that the dishwasher was not secured properly to the cabinet.
So when I opened the door to the dishwasher it would cause the dishwasher to lean and tip forward a bit when opened.
After installing the screws to the brackets at the top of the dishwasher it no longer tipped forward.
There should be a few brackets attached to the top of your dishwasher that should be visible when you open the dishwasher door and then you can install a couple screws to secure those brackets into the countertop.
Then the dishwasher should no longer tip forward when the door opens.