Oh yeah, they can scream when they feel like it. Sometimes, their nervousness feeds off the owner's and vice-versa. Since you trust your vet, it was probably wise of you to go when you did.
When Assumpta had her big dental cleaning several years ago, she had to stay overnight (which I'll never do again, BTW). I got a call from the vet's office at 7:30 AM asking me if I could come and get her early, before opening, because none of the techs could get near her and she was upsetting the other animals. They had to use rabies gloves and scruff her to get her into her carrier for the ride home. The vet prepped me on what to expect when she got home, and I was NOT looking forward to dealing with psycho-kitty for a few days.
The foolish cat walked out of the carrier, slashed her tail around a few times, hissed at me (but very conversationally, like "Man, I am having SUCH a bad day!"), ate a whole bowl of food, then fell asleep on my lap. Two hours later, the tech who crated her called to see if she was being difficult, and I related the above on speaker-phone for everyone in the office.
But be prepared for some extra aggression to people and other pets while she gets used to her own territory and space again. Your vet should give you some post-op instructions on behavior and medical things. They usually get over vet visits (though you may have to be sneaky next time you put her in the carrier). I'm glad she's spayed now, and I hope it helps with her aggression in the long run (just be ready for a couple days of very annoyed kitty).