Two at once, then. That's probably why he's feeling a bit off.
Sleepiness is normal as long as it doesn't last for too many hours. He should be normal today (being a kitten).
The extra meowing could be from yesterdays stress or because he's sore from where the vacs were given. Believe it or not, some cats will complain if they're hurting - I have one that got a sore leg from a vac and he definitely told us about it.
