If that's the case then yes more caution is necessary. That's why I like to supervise the first couple of visits between chicks and adults, to see how they fare overall as a group, who the problem hens (if any) might be, and how effectively the chicks run away/hide if there is a pursuit.The difference is that the older birds are actively and aggressively going after them, rather than giving them a peck on the head if they get too close. That's how it's been in my experience.