If anyone wants to argue -- and it would seem natural to argue --- that everyone is a sinner, it would have to be admitted that an exception was made for Mary, especially considering the exact, and utterly unique way the God's messenger had to adopt an entirely new word in order to express it.
It's a one-off event, a real Singularity, expressed in this wonderfully concentrated idea from the lips of God's ambassador, this singularity of a word.
It acquires more theological depth when you think of Mary as the New Eve, and as having been prefigured by the Ark of the Covenant.
No he didn't/
Sinners need grace. Anyone without sin doesn't.
If Mary had no sin, then she didn't need grace.
I have that same grace freely bestowed on me, BTW.
Mary and Grace
The word grace used in this passage in Luke is used in one other place in the Bible and that is Ephesians 1 where Paul is us that with this same grace, God has blessed us (believers) in the Beloved. IOW, we all have access to that grace and it has been bestowed on us all.
http://biblehub.com/greek/5487.htm
Luke 1:28 And he came to her and said, Greetings, O favored one, the Lord is with you!
Ephesians 1:4-6 In love he predestined us for adoption as sons through Jesus Christ, according to the purpose of his will, to the praise of his glorious grace, with which he has blessed us in the Beloved.
Greek word grace
charitoó: to make graceful, endow with grace
Original Word: χαριτόω
Part of Speech: Verb
Transliteration: charitoó
Phonetic Spelling: (khar-ee-to'-o)
Short Definition: I favor, bestow freely on
Definition: I favor, bestow freely on.
HELPS Word-studies
Cognate: 5487 xaritóō (from 5486 /xárisma, "grace," see there) properly, highly-favored because receptive to God's grace. 5487 (xaritóō) is used twice in the NT (Lk 1:28 and Eph 1:6), both times of God extending Himself to freely bestow grace (favor).
Word Origin: from charis
Definition: to make graceful, endow with grace
NASB Translation: favored (1), freely bestowed (1).