User blog comment:Omega natsu2/Episode 182: The Burning Earth, Review./@comment-24748439-20140517125916/@comment-7418318-20140517145248

Which isn't technically wrong, since maiden and virgin have pretty much the same meaning.

That Virgo appears as a maid is just a jab at the constellation of the maiden.

Either way it's just an error by the subbers rather than Aya Hirano, since Lucy says the same thing she always said "Hirake shojoukyu no tobira! Virgo!" or something similar-sounding.