Is it weird for your girlfriends parents to be over protective?

I’ve been dating this girl for all most 2 and a half years now (1½ years the first time we dated and all most 6 months now) and her parents are very protective of her. they won’t let us together with out her brother with us and my girlfriend is aways scared that her parents will find out about something we did at school or when shes with my family.