I am concerned about the girl my friend is dating

Okay moms please give me your advice on some thing I am trying to tell my friend that the girl he is hooking up with is acting weird First off she comes over to do laundry at his house and then accidentally leaves two bras underwear two pairs of booty shorts which was weird but Ok also her cups and is writing her name on things in his house…. Is it just me or is this werid, stalker ? They have only hung out a couple times…….