I have had my two little girls for sometime now. One is 6yrs and the other is 5yrs. Just recently the 6yr old has been turning around and hissing then swating at the other one then running off. I'm wondering is she playing with her or is she mad at her for some reason. Sometimes I think she just gets fed up with the other.
I really think they are just telling each other to back off. I have seen this in Cole (my 7 year old spayed female cat). She is a lot grouchier then she was as a young cat. She even hisses at me when she is upset. Then it is like I'm sorry Mom and comes and sits on my lap or kisses me.
Then you turn around and the cats are sleeping together all curled up. She just gets her crabby times. LOL