Spock had read Earth mythology in the past to know that every great hero had a fault or a flaw. They all had, as the saying went, an Achilles heel. While he did not believe himself to be any great hero, he was swiftly becoming aware of his own Achille's heel.

Spock's control was legendary in Starfleet. He was always, ALWAYS well-kept, even-tempered, and intellectually sharp. Spock had no interest in allowing anyone to believe otherwise. So, when he was asked to be a key member in a diplomatic party to a new federation planet, he had no reason to believe this mission would be anything but beneficial to his professional development.