I wouldn't worry too much. Cats are pukers by nature. If something doesn't agree with them, they eat too fast, they have a hairball, etc. they vomit.
I would keep an eye on your kitten just to make sure she's eating/drinking/pooping/peeing normally and if she continues to vomit. Also observe her personality. If she starts to become withdrawn, hiding, shivering, or some other weird change, consider a vet trip.
Almost forgot.. vomit can have many consistancies that can indicate different things. If she eats dry food and it looks the same coming out as it went in, she probably ate too fast. If it's clumpy with some fur in it, probably a hair ball. Just a small amount and mostly just saliva, possibly she smelled something that made her nauseous (Pippin does this sometimes. Ground coffee and sharpie pens trigger it.). Look for plants or foreign objects in it. Sometimes they get into things that are toxic or are just not good for them.
Like I said, it's pretty normal so try not to worry too much.