Smooth, striped, brown, and 4 cms makes it probably Noctuoidea or Geometroidea. A lateral view would have been helpful, as the different families / subfamilies of these have either 2, 3, 4 or 5 pairs of prolegs. Did you try and rear it to get a moth for an ID ? It is interesting that it fed on Lomandra, as it is clearly none of those listed at the foot of http://lepidoptera.butterflyhouse.com.au/plants/aspa/asparagaceae.html