My 4 month old kitten threw up a white foam like liquid, it was a little bit and only once, he haven't eaten since (3 hours). Right now he is a little quieter than usual, he pooped normally earlier. What could it be? Should I be worried? Should I take him to the vet?

He is an inside cat and was dewormed 6 weeks ago, so I don't think worms may be a problem.

Please help guys, I don't know if I'm overreacting. Any help will be appreciated. Thank you.

Small update: he stand up, stretched, groomed a little bit and is trying to play. It looks like he is on a better mood, but also he went straight to his food bowl, smelled it, tried to eat some wet food and gave up. So, he is playing at the moment, but not eating.