Well, we don't say she was God, so I dunno how that follows. Plus, all the prophets were clear that it was God working through them, not them doing it themselves.
(And I don't mean giving birth to God incarnate, that was not something she stood up and did, but was placed on her by God.)
Again, just like the Prophets...it was not her that was doing it but God doing it through her. But I wouldn't take Mary's will out of the equation either: remember..."Let it be done to me according to thy word." That's an assent, however you slice it. She could have said "no" as Jonah once did.
The Divine Praises
Blessed be God.
Blessed be His Holy Name.
Blessed be Jesus Christ, true God and true man.
Blessed be the name of Jesus.
Blessed be His Most Sacred Heart.
Blessed be Jesus in the Most Holy Sacrament of the Altar.
Blessed be the Holy Spirit, the paraclete.
Blessed be the great Mother of God, Mary most holy.
Blessed be her holy and Immaculate Conception.
Blessed be her glorious Assumption.
Blessed be the name of Mary, Virgin and Mother.
Blessed be Saint Joseph, her most chaste spouse.
Blessed be God in His angels and in His Saints.
May the heart of Jesus, in the Most Blessed Sacrament, be praised, adored, and loved with grateful affection, at every moment, in all the tabernacles of the world, even to the end of time. Amen.