Does anyone else's kitty do this?

Lu's been doing this thing where when she throws up, either on the carpet or in the kitchen, she'll stop and try to cover it up, like after she's done in the litter box.. and I'm confused, because she does it every time, and you'd think she'd know that she's not covering it. Does anyone else's cat do this?

One of my cats does. But, she tries to cover up her food, too. I think it might be their nature--to hide everything that may have their scent on it, like they do in the litter box. That's just my opinion, so if you get a scientific reason, please let me know.