Answer:
Subtle reminders or suggestions
Explanation:
The unconscious mind is comprised of mental processes that are inaccessible to consciousness but influence judgements, feelings, and behavior (according to Wilson in 2002), and following Freud investigations in 1915, the unconscious mind is the primary source of human behavior.
When Simon's friend asked about his back, the unconscious part of his mind reminded him the pain he suffered for several days on the couch, even if he was not feeling pain at the moment, and he was fully recovered, the call acted as a reminder or suggestion that if he did not want any more back pain he had to be careful, not to protect the area necessarily but to protect Simon from pain. The subconscious is reminding the conscious mind that back pain was bad and it should act accordingly to prevent it.