Hi,
No, the smooth plastic is never a problem for her. In fact, my bunny prefers it to a fleece surface as well, even after she was spayed and was tender underneath. So don’t worry, she’s just telling you what she likes best.

I would suggest that you use something besides pine shavings for her litter. Some studies have shown pine chips and shavings, and cedar chips, may be harmful to the bunny if ingested. You can easily substitute it for one of the assorted litters recommended for buns. If you like the pine (and my bunny likes it best), try some products called Feline Pine or Equine Pine. The Feline Pine is small pellets that soften with moisture so they soak up the urine but still smell like pine. You can buy the cheaper one for cats – mine is in my grocery store. Other products that people have had success with are Yesterdays News or Care Fresh. If she likes the fleece, the closest match to that sort of feel would be Care Fresh. Just be sure to keep it in her litter pan so she doesn’t get confused, and to put a small amount of soiled litter in there to start so she recognizes the smell as a place to go. She’ll be trained in no time.