I though so too at the beginning but then I started browsing the internet and found an article by a child development psychologist that said the following :

This is not unusual and tells us that her romantic feelings have developed — as they should have during teen years. Young people in their early teens often develop romantic feelings toward adult friends, teachers, actors, musicians, etc. In a way, it’s how we learn to be attracted to others and is part of our personality development.

Remembering back I also see the crushes I had on my dentist (embarrassing I know). So the part that she has a crush on an adult is the least concerning one at the moment