My four year old cat, vomitted twice this week. It wasn't whole pieces of food though, just a little yellowish-orange saliva-spit (kinda like his dry food color). This is the first cat I ever had, so I am not sure how serious this is. From other posts that I've read, it seems that whole pieces of food are thrown up, cause of maybe overeating. But he doesn't exactly do that. Otherwise, he seems fine, jumps up and down normally, alert as usual, eats, drinks, poops normally, no change at all. Today, he even ate right after he threw up. He even had the decency to throw up on the kitchen floor, and not on a carpet. He also constantly licks plastic bags, but he has always done that. Again, I am not sure how serious this is, I am kind of a hypochondriac myself, so I just think that I am too paranoid on this. Should I be worried though?