Take a wide flat blade screwdriver to the door side and spread it open a bit more. Should make it tighter. Had to do that right off the bat with drawer under the oven. I literally made my first left turn out of the dealer driveway and the thing flew open.
It must be loosening because it's starting to slide open again.
I had a question for you the other day, but I forgot what it was....oh well.
Edit: If that doesn't work, maybe buy some those command Velcro strips, cut one length-wise to fit inside the door edge. That'll keep it closed. Cheap fix. Did that on the medicine cabinet door. Got tired of the contents ending up in the sink