Relating this to Cialdini's Influence, I'd wager this is due to reciprocity. Whether real or not, when you apologize, you're making a concession which triggers

Relating this to Cialdini's Influence, I'd wager this is due to reciprocity. Whether real or not, when you apologize, you're making a concession which triggers the "click, whirr" effect described in the book. Persuasion is a fascinating topic.