Nocturnal Semantics

The opossum is certainly a synanthrope, but still generally reclusive and nocturnal, and so when the dog and I saw a mottled stiff tailed creature ambling across the road this morning, it took me a second to realize it wasn't a very ugly cat-- and then I wondered what it was doing up at this hour, and if a nocturnal creature is up early in the morning, walking groggily, does that mean it's up early or has it stayed out far too late late?