I have to say I disagree a bit with both answerers but at the same time I agree.
first off, girls at 14 (especially nowadays) are looking to tempt men so, sorry lesae, but girls are maturing or at least thinking they are maturing sexually a lot faster than in my day. She might be trying to tempt, if:
1, you are a very handsome man and she doesn't approve of the relationship you and her mother have so she's looking to create problems.
2, if she has been having a lot of problems with her mother and wants to get back at her.
3, she doesn't like you and wants to find a reason to break up her mother and you.
4, she's curious with her body and wants to know how powerful it might be.
then again she might not be tempting you at all and like brokenheart said, she's just not used to having a guy around the house and it's a behavior she was used to showing at home before you arrived, which in my opinion is the most likely scenario.
now, as they said if you are thinking she's tempting you then the thought is quite scary as this means you are looking at her with different eyes, ones you most definitely shouldn't use on her.
talk to her mom and set the rules, tell her it's unacceptable to go around the house that way and just forget the whole thing and stop thinking about it before bigger problems arise.