They might have real genuine concern, are you a vulnerable person in some way? Are you very pretty and get preyed upon by guys a lot? (1000 followers in that amount of time could be a lot depending on how it occurred). There are likely a lot of guys on there just wanting to hook up with girls for sex and not care about her, i.e emotionally, pregnancy, STD's, and will just move on, or guys that will harrass women and try to control them by being mean and abusive.
Other that do you come from a religious background, Muslim, etc? That's often comes with a lot of control from parents though may not be a bad thing if they are looking out for you.
If none of that applies them possibly you might have parents that struggle to let go of the child rearing phase as its territory they gave become accustomed to. They may just be genuinely concerned and protective but don't realise that by not allowing you exposure to any risks that could have a negative impact also in you not learning to be street smart and experiencing life as other people do even if it is at some times negative. That said there are some real psychos out there and they try and dominate others without their consent and can be a nightmare getting them to f*ck the hell off and I say that as a guy from stuff I've seen happen to other people.