Not necessarily. The angel only announces a future event. A girl expecting to have sex in the future would not automatically jump to the conclusion that some other thing must be meant.
Certainly the nearness to the wedding could lend a factor, but nothing that is definite.
On the other hand, a woman with no intention of ever having sex certainly would ask such a question.
SD
All of this is speculation because we don't know what was in Mary's thoughts at the moment.