Advice for roommate question please?

my roommate has been acting a little out of sorts lately...and I think that the end of the semester just exaggerated it more, with the stress of having to write papers, final exams, etc. But she started to treat me really weird, like when we p by each other she pushes (kind of aggressively) ped me. Today she left cash on the refrigerator door for he utility bill. I prefer she pays me her share of the bill in person, so that there's no issue later on of "I left it on the fridge, why didn't you get it", etc. It's just more solid and final when it's in person. do you think i should reinforce that?