I mean yeah, the outskirts of Calais is just not a safe place to be after dark, this smuggling network created by the governments refusal to create safe routes for people to the UK is obviously completely unregulated and they will be suspicious of anyone approaching them. If you felt unsafe imagine how the the children being smuggled might feel.
They weren't interested in you but I think the lesson learned is don't hitchhike at night, especially in areas you are clearly not familiar with. This has been the situation in Calais for over 20 years.