Waddles:
Part of me totally agrees with her but another part of me is suspicious, as though we both know that things are going to happen between the two of us.
I think you could very well be right on the money here.
Given the situation, living in close quarters with each other, I can't imagine that something wouldn't happen. One if you is going to start liking the other if one or both of you don't already.
I'll play this out a little in my head here. I'm not saying any of this will be the truth, I'm just thinking about what it could mean if I was in the same or similar situation. This is just me, I know nothing about your ISFp friend.
The fact that she put her face in yours obviously means she's already fairly close to you and comfortable with you. Yeah, she may be testing. She probably wanted to see what your reaction would be (I read a lot into facial expression) and if you would do something in return. She may already have hopes that something will happen but is just saying that she'd have to leave because she's not completely sure where
you stand on things, hence, the "test". My experience with the ENTp I know is that he's rarely ever straightforward with exactly how he feels, and often I wonder if he even knows exactly how he feels (I have no idea how you are) but she might not be completely straightforward with her own feelings if you're not straigtforward with yours because she doesn't want to get hurt/be rejected/lose the friendship.
Did she say what her reasons were for having to leave if she started to develop feelings for you? It seems unfair somehow. Like, its ok for you to have feelings for her, but it's not ok for her to have feelings for you. It's almost like it's some sort of manipulation. Perhaps it's a way to get you to confess your feelings, if you have any. It seems like kind of a trap.
Of course she could really mean what she said about leaving if she ever has feelings for you. I don't want to steer you wrong, these are just things that came to my mind and it doesn't make it the truth, I just thought I'd offer some things for you to consider.