If there are further behavious concerns I would put it down more to 'acting out'. Yes it can be normal for teenagers but it would really depend on the extent of it and the behavoours exhibited.
My suggestion (since the adult relationships are not the best) is to talk to her. Do not accuse her of anything but just talk. Let her know you love her no matter what but she can alwaya talk to you about anything.
Teenagers are still very vulnerable when it comes to feelings and behaviours. Govw her reassurance.
The original scenario I do not find a concern necessarily but if it does concern you and your DH then talking to her is the place to start. Good luck.