It is sometimes said that Mary’s surprise was because it was not
customary for a man to give a greeting (ἀσπασμός, 1:41, 44; 11:43; 20:46) to a
Jewish woman. But the rabbinic evidence is late and scanty (SB II, 99), and
Mary’s wonder was occasioned more by the character of a greeting which
addressed her in such exalted terms, and implied that, like the great men of OT
times, she was chosen to serve God and to be empowered by him (W. C. van Unnik,
‘Dominus Vobiscum: The Background of a Liturgical Formula’, in A. J. B. Higgins
(ed.), New Testament Essays, Manchester, 1959, 270–305). (I. Howard Marshall, The
Gospel of Luke: A Commentary on the Greek Text [New International Greek
Testament Commentary; Exeter: Paternoster Press, 1978], 66.)