My female rat terrier yorkie mix thinks she is a boy?!!!?

so my newest addition to the house saydie is a female terrier 10 months old and she has been living with us for about a month now but recently she started trying to mount my male dog sam who is 5 he just kinda growls at her and walks away but she has also been scratching at the carpet trying to dig..... why is she doing all this should i deter the behavior or let it run its couse because of course nothing will happen right?