My kitten's brother and sister came over to play and now my cat hisses at me...why?

My kitten's brother and sister came over to be introduced to her because they would be staying with me for a few days. I put my kitten in the bathroom with her things. When I came in the bathroom she looked very scared so i tried to comfort her and she kept growling and hissing at me. Is it because I smell like her bothers and sisters (who were much more accepting of her than she was of them) and she is afraid of them? When is it safe for me to pet her again? I felt so bad and now I'm thinking of getting another kitten so she won't be so afraid of other cats.