Only nauseous for one day?

I guess I’m one of the lucky ones and don’t experience a lot of morning sickness. When I hit 6 weeks I was pretty nauseous for maybe 2 days and it went away. I’m 9w3d today but yesterday I threw up and was extremely nauseous most of the day. Today I’m perfectly fine. I’m just curious on if this is normal? I’m not sure why it only was for a day. I mean I’m thankful just confused