Willa - no bed rails

In March we took the bed rails off of Willa's bed.  She has done a great job of staying in bed, which must be hard for her.  However, there was one night about 2 weeks ago when we heard crying - Karri and I looked at each other with the look that says, "who is going to have to deal with Willa."  It was me and I found her lying in a mess of comforter, lovey, blankie, and a pillow.  She had fallen off.  Fortunately it was a soft landing and she was unhurt, but she was surprised and unhappy to not be in her bed.