Sounds like she's attracted to transmen in a physical way. Nothin wrong with that. Just that when she dates she should be open about her feelings and treat transmen as whole people, not sex toys. In other words hold herself to the same standard she would date anyone with. You can be into men with penises, women with vaginas, women with penises, men with vaginas, etc.. just as long as she remembers they're people first there's no problem.