Bed above is this size:
The mattress measures 30" wide and 73" long, as compared to a twin which is normally 39" wide and 75" long.
Also saw an older post here that says moderates murphy beds are 30″ wide by 64″ long so it seems the DVC ones are longer and pretty close to a twin bed.
And from photo above, at Poly, it looks like maybe the mom was sitting on the edge when it pulled out of the wall...just my guess. Or rolled to the edge like to pick something up off floor. But it should not have pulled away from wall. A couple people jumping on edge might make it pull away. Or not being secure properly.