It's just something they say. All three of mine have had their legs spread as wide as possible, so there's never been any question of gender and we've always heard the tech say something similar.
Congratulations! And good luck on the name. We always went with a name we loved and then found a family connection - it worked well (although we were running out of boys names, so we were glad this one was a girl because we had a name all ready lol!).