Feline Non Recognition Aggression - are we doing this right?

Hello, sorry to be another post about this subject! Our girl cat was taken to the vet this morning at around 9am to get her teeth cleaned and some extracted, and we picked her up around 3pm and got home at around 3:30. Our boy cat, who is normally just a big oaf, started hissing at her when we laid her on the towel in the living room as she was still coming out of anesthesia. He hasn't really hissed at her/in general since we adopted her 4 years ago and we did the slow introduction method. Immediately after he hissed, I'm a little stressed. I start googling while my partner lays on the floor with girl cat and creates a boundary with his body around her a little bit. He's not really hissing now, just acting a little off. Girl cat is zonked and giving no reaction.

I found out about feline non recognition aggression pretty quickly, I had no idea! The last time they went for vet visits was at a pop up clinic 5 min away from us to get their boosters. We took boy cat first (30 min ordeal) and then dropped him off and picked up girl cat (another 30 min.) There were no issues when we did this and things went right back to normal, but after reading online I'm guessing it's because they were both exposed to those same smells/experience so there wasn't really a staying cat/going cat dynamic. They have been good friends since the introduction 4 years ago, playing often and able to live in peace up to a up to a week while we take trips and have a neighbor check in on them daily in the afternoons for food/water/affection.

Flash forward to now, as I'm writing this, its been around two hours since we got home. We've placed girl cat on our couch on top of a few layers of towels. After reading more posts on here, I've put a couple dirty socks and a towel I used this morning around her bc boy cat is a little weirdo and loves our used socks/underwear/towels (he's an orange.). It's been a few hours, there hasn't been a ton of hissing or trying to initiate fighting on his behalf but the energy is definitely off. He was laying next to me on our other couch (they're still in the same room since she's come home and we haven't separated them) and he gets his claw stuck in the fabric and gets over stressed for a second and mini-hisses at me as I go to help him as I always do. Now, he's gone upstairs to nap on our bed while girl cat is still zonked on the couch. He's basically separated himself from the situation to take a sleep.

The point of this word vomit is essentially to ask you all if you feel this is okay or if I should be doing more. A lot of posts on here on this same subject included comments telling OP to separate them and do a slow scent introduction as if they are meeting for the first time again. I'm anxious because partner and I both work 8-6:30 and aren't able to leave our workplaces long for lunches, and we both work tomorrow. Any advice? Anyone whose cats had some aggression but it ended up not needing to be a full blown intervention? I'm just looking for some confirmation that these situations aren't always horror stories that take weeks to resolve and sometimes it's just weird vibes for a little bit. Thank you for reading, all comments welcome!