The quote suggests that when someone behaves in a manner that is inconsistent with their usual character, it is often an indication that they are facing underlying issues. This observation highlights the importance of understanding a person's typical behavior and recognizing deviations as signals that something may be troubling them.

The author, Alexander McCall Smith, emphasizes the commonality of this phenomenon in human interactions. Frequent encounters with this pattern reinforce the idea that unusual behavior often stems from deeper problems, prompting the need for empathy and support when witnessing such changes in others.