Where does the idea that Jesus was perfect come from?
I know some have considered Jesus's celebacy part of his perfection. As Mormons we have no problem with the possibility of Jesus being married but might with his wine drinking.The perfection of Christ is a principle in Christology which asserts that Christ's human attributes exemplified perfection in every possible sense. Another perspective characterizes Christ's perfection as purely spiritual and moral, while his humanistic traits are subject to flaw, potential, and improvement as part of the current human condition.
Apostle Paul's perspective on Christ as the "perfect man" considered him the "second Adam" who brought forth life, while Adam left a legacy of sin, e.g. in 1Corinthians 15:22 and Romans 5:12 
In the 2nd century, Saint Irenaeus of Lyons based his concept of the perfection of Christ on the Gospel of John (as well as the other Synoptic Gospels) rather than on the Pauline Epistles. For Irenaeus the perfection of Christ originates from his being "The Word", i.e. the Logos which pre-existed as Christ in perfect form, untouched by sin: because he was the first, he could achieve perfection.
In the 3rd century, Tertullian emphasized the perfection of Christ as a key consequence of the Incarnation of the Logos in Christ. In Tertullian's view to suggest that anything could be added to improve Christ would be to deny the Gospels.
In the Middle Ages a key focus of Christological studies on the knowledge of Christ was his perfection as in John 1:14 which states "full of grace and truth". In the 13th century, the perfection of Christ was subject to detailed theological analysis by Saint Thomas Aquinas in his Summa Theologiae.
John Calvin considered the perfection of Christ as a source of grace which covered the blemishes of sin in others.
It doesn't appear to be anything he claimed for himself. To be "full of grace and truth" does not seem to match most definitions of perfection. One definition of Perfection is to be complete or fully developed - but if Jesus grew from grace to grace at what point was he fully developed/perfect. From an eternal perspective of continuing progression is there such a thing as full development.
But more to the point - why would Jesus even have to be perfect? Was it not enough that he was the son of God? or that he was willing to offer himself for us? Would a lustful thought from a 13 year old Jesus have destroyed the entire plan of salvation?
I am interested in your perspectives.