The sighting, as described, could be an example of 'absorption'. Remember the sentence "
My mind was in neutral reaching the end of a long night with not a lot happening". The witness may have been in a trance-like state as a result of a long time cycling around without any distraction. It is similar to the 'time loss' often reported by people who see UFOs while driving at night. In such a state people can fantasize.
The main point of interest in the story is that someone confirmed that the place in question was haunted. However, they did not explicitly mention any details that corresponded to the witness sighting, like appearance or actions of the ghost (unless these details were simply omitted from the account). Thus, it is effectively just a coincidence. If the witness had reported the sighting in a different house nearby, the story would lose much of its impact.