Any significance when a modest-dressed woman wears an incredibly low cut top out of the blue one day?

Alright, so I work with a female co-worker. She is usually reserved and dresses modestly. But today she enters work with a low cut top; so low that she had to constantly readjust it frequently. Plus she bragged to the other women how she got a pedicure and manicure. Not only that, she says her husband is out of town for the week on business. I have no intentions of pursuing her. Repeat: No intentions. But I was wondering if there is any underlying significance in her abrupt change of appearance. I mean, if you work closely with a male co-worker, would you not want to give off the wrong impression? I know if I was a chick, I would be aware if I wore a shirt that practically exposed my chest.