sounds like it's normal for her...

It is normal to look to ones future. It is normal to be attacked to potential mates. It is, however, inappropriate to dwell on such things (let alone act on them) while one is serving a mission. I don't know you or this Sister. So, I can't judge what to think of this particular situation. My advice to you would be to not do anything to encourage her to think of you romantically while she is still serving. However, if you are attracted to her and would be interested in pursuing a relationship, then you could let her know just before she goes home. - BTW, are you a single male who is living alone? If so, then it really would not be appropriate for these two Sisters to be meeting with you anyplace private (your home for example). I am a single male living alone and when the Sister have stopped by my apartment, we just talk at the door. I don't invite them in and they would come in if I did, at least not unless there is someone else there to serve as a chaperone. The reverse also applies to the Elders. They should not go into the homes of single women either. The reason for this is to protect them from the appearance of impropriety and even potential false accusations.