I don't think it's a big deal. I think these are one of those small things that can be worked up into something much bigger if it's not dealt with logically. If it was something an ex said, well, it's not to uncommon. It probably has A) nothing to do with the ex, and all to do with B) her intimate attraction to you. She may have heard /them/ say it, but she wants to hear /you/ say it, which shows that she is very much attracted to you.

Remove the ex from the equation and see that it has more to do with her wanting something sexually from YOU over something she used to have.