I don’t seem to be able to reproduce the issue.
Could you please post a screenshot to illustrate your point?
As for jagged edges I wonder if the image may just be too small to yield good results.
Not sure if it will make a difference. But update to 13.0.1 and see if that helps. Also try trashing your preferences by holding down Shift+Option+Command keys AS you launch Photoshop. You'll get a small dialog to confirm resetting of preferences.
you must have an older video card (like me I have a Nvidia 120GT). CS6 liquify doesn't work well with the older cards. It creates that distortion you are seeing. What you have to do to fix it is launch liquify in non-GPU mode to get CS5 quality with your card. Hold down the option key when launching liquify. You will see a 1 pixel black border around the preview dialog box.