Is she being courteous? or is she "rescheduling"?

I think this girl likes me (she is on the shyer side), but im not sure, today I asked her to go study with me after school on the next midterm(Tuesday). I know she knows that I know the material and act stupid around her. She seemed surprised and asked "now?", I responded yeah, and she was like "yeah sure", then my stupid friend went up and said "i thought you said you couldnt study today". I wanted to study with her and my friend ruined it, i said "oh yeah, dang i forgot I have to pick up my sister today". She was like oh its okay, we can just study on Monday after lab. Is that good or was she being courteous? She didnt seem too excited, but she wasnt weirder out or anything, and was like alright I'll see you Monday and left.