Why do my cats suddenly loathe eachother like a bad can of tuna?

So, I am sure all of you will be thrilled to know, I got all 3 of the 2-year-old girl cats spayed three days ago. They are all fine, except for one thing…every time they come within a foot of one another, they growl and hiss! These are cats that used to love eachother and lick and clean one another and sleep together happily…I have read that this is pretty common in cat families after one comes home from the vet…perhaps from the “vet smell”...but shouldn’t this go away after a short time??

By the way, I no longer have the pee problem…so far!