Our 4 1/2 y/o did something Ive never seen

shes been an only cat since we rescued a mama and her 2 kids. well i put the kids in the living room to keep them away from their mama who was just spayed. Our 4 1/2 y/o (Punkin) has got use to them where she doesnt hiss that often anymore. she actually plays with them

here are what i like to call "the rugrats" they are 10 weeks old


well punkin was hiding behind something in the "attack mode" and did the whole "arching her back-walking sideways" thing. Ive seen the kittens do it when they play fight but never our own cat. so anyways she did this and pounced on the smallest one, Stitches (one on left) Is this behavior ok? i got scared cause she is so much bigger than they are. in comparison to the mama who is 7.5 lbs...Punkin is 15-16 lbs

i would think punkin is a playfull cat sometimes cats do that over territory but it doesnt sound too serious as long as shes not biting them, i think shes just playing with them,if she does start to get rough there may be trouble ahead,i have two cats who dont get on due to age difference but they never try to kill eachother so i wouldnt worry too much, youll know if she/hes being serious