$_cached values could be cleared only in destructor method, meanwhile behavior might already detached and owner property will be nulled, so get_class($this->owner) values will be wrong. Also, maybe, it is sensible to clear $_cached values with behavior detaching .
There is no more possible memory leaks inside behavior for Yii 2 release version. Also working approach was changed. We can complettely forget about troubles like this.
$_cached values could be cleared only in destructor method, meanwhile behavior might already detached and owner property will be nulled, so get_class($this->owner) values will be wrong. Also, maybe, it is sensible to clear $_cached values with behavior detaching .