Heat buildup from too much RPM might cause distortion, or breakdown of the acrylic surface even causing crazing (fine cracks). Some acrylics are harder than others too. Polishing in one spot too long I've seen can cause distortion. It behaves like an optical lens if you take off too much material, say if you focused too much polishing on one spot on a deep scratch with your finger. You want to spread the repair over a larger area like I do when fixing a dent in body work, using a cross hatch sanding motion. Another trick s to wrap your polish cloth in a foam sanding block, 3"X3" square this keeps everything nice and flat and polishes evenly.
I would stay away from paper towels with all due respect, these will leave very fine scratches, if you do use them, use paper towels in the coarse stage, I use the softer thicker shop towels from auto parts dealers and then use the better cloths (super fine and soft microfiber cloths) in the polishing fine stage. Polish cloths, rags, paper towels make all the difference in the end product. One piece of grit and start over, so cleanliness is of absolute importance!