It could be a fur ball. Sometimes cats gobble their food too quickly & bring it straight up. They are usually hungry a bit later. If they have dried food & drink too much water it blows up in their tummy & they can get sick.
Cats just seem to be randomly sick, very often. Having around 20 cats myself rarely a day goes by without my discovery of a pile of cat sick somewhere in the house. On one memorable occasion, when my mum came to stay, a cat was sick in her shoe ....
Sometimes cats are just sick for no reason, just keep an eye on her. If she's still eating and drinking and running around fine, it's probably just one of those things. If she does seem ill though get her to a vet, cats are good at hiding when they're ill.
Cats just vomit - some more than others. We had one who did it all the time and there was nothing wrong with him. Wee bugger used to always do it right underneath the bed on the cream carpet. If the cat is acting normally I'm sure she is fine.
She had her morning pouch as usual and when my husband came down yesterday morning she had been sick but have no idea why. I never leave food out in the kitchen so she can't have eaten anything she shouldn't have. She was running around everywhere too and didn't look poorly and I couldn't see hair in the sick (sorry if people are eating!)
I have made sure she has fresh water and dry food which she has at lunchtime and she seems ok with that but when should I put her back on pouches? She must be hungry now surely.