Random nannying question:

I've nannied for about 10 years and I just started nannying these two girls. All the other kids I've nannied want to interact with me and spend time doing puzzles/Games. But these girls will often go in their room and say "we want to be alone" is this normal?  Do they just not like me? Should I just give them space or try to get them to play and interact more often? Mom advice/ or nanny advice (or any advice) appreciated.