He also laughed. Both were signs that he was embracing his human half, having learned from Vejur that the non-emotional ideal he had sought was "cold, barren."
It is possible, though, that a Vulcan aged 20 to 25 is not expected to have such total emotional control--it would explain Spock's emotional displays in "The Menagerie." For a race that lives a quarter of a millenium, full adulthood might not be reached until the thirties or so. Saavik's tears--like Spock's grinning at the Talosian flora and exclaiming "The women!"--could be chalked up to adolescence.