In this case, the reflexive pornoun, itself is used as an intensifier. It is considered standard usage.
"Sometimes, the reflexive pronoun is added to highlight its antecedent. A reflexive pronoun used in this appositive way is called an intensive pronoun and, in English, is accepted as standard: for example, "I, myself, wrote this" and "We gave the card to our parents, themselves"
Reflexive pronoun - Wikipedia, the free encyclopedia