Its pretty normal for a hamster to have different sleeping spots, like most animals, hamsters will sleep wherever they are comfortable. That may mean picking a different spot regularly or having the same spot for a while.  Either way, if your hamster is sleeping in different areas, its not normally a reason to be concerned. However do be aware that your hamster may be avoiding dirty or soiled areas of their cage, which can also be a reason for a hamster to sleep in different spots.