I think you probably dreamt of her that night because you probably had thoughts about her in the back of your mind, and so you dreamt of her in your sleep.
Just to make sure things are ok, i think you should phone her or try to get in touch. In Islam and in some cases in dreams we meet other souls in our dreams and some are recognisable and some aren't. Some will remember who they saw but if you know someone you saw in your dream and ask them if they saw you in their dream, they'll probably say no because they don't remember.
Everyone is different and sleep in different ways, but you can be sure if you had a genuine dream if you slept in the correct Islamic manner. (On your right side, saying prayers before going to sleep, being clean and wearing clean clothes and dreaming just before Fajar salah before the Adhan).
I am not a dream interpreter, but this is the advice i can give you.
Thank you for the question.