Is your cat constantly throwing up? Are they hairballs that they're throwing up? Blueberry throws up sometimes too, and they're only hairballs. I think that's pretty normal so we don't worry. And also he seems ok after.
If you're saying that your cats are as healthy as can be, then I won't worry. I'm guessing its only hairballs if they seem ok after throwing up. But if you're really worried, then mayb a checkup at the vet would be good.