@jennythelib - Yes, the phrase "O2 sats" refers to the oxygen saturation of blood.
I had a C-section after a long labor and I remember having one of those finger monitors afterwards. They were not quite happy with my O2 sats even though it was never below 90 (I want to say it was about 92). I'm no doctor, but I think even though it's not officially "bad," they often treat it to make sure it doesn't get lower and to try to reverse the trend.
In my case, they would remind me in the recovery room to take deep breaths. When that didn't work, they put one of those tubes into my nostrils to get me a little more oxygen. That was, by the way, incredibly uncomfortable and made my nose very dry. I was so happy when the night nurse took it out a bit later.