So is she into me or not?

There is a girl that I know only slightly, because I work with her sister. We have talked a few times and she seems cool, and seems to have a good sense of humor (ie.. she has laughed at my dumb jokes). However, we haven’t hung out or talked intensely or anything like that.

One day she writes me via Facebook saying her sister suggested me as someone to go with her to a concert. Sadly, I couldn’t make the day on short notice. Then a few days later she writes me saying since the concert didn’t work out we should hang out; maybe watch a movie. i say it sounds great and add food to the night, to which she does not object.

Is this possibly a move? I certainly wouldn’t mind getting to know her. She’s beautiful as well as funny, and smart. Am I jumping the gun here, or does this seem like there is a testing of the waters going on here?