No, that's far from normal. Gravity should always pull everything towards the center of the planet no matter where you are on it.
I have seen this bug happen once before though. I was watching someone play on Twitch. They got out of their lander and fell away from the planet for no obvious reason.
It's one of those rare bugs that makes no sense. It should never happen. I imagine it's caused by some unusual combination of actions.
So don't worry. You should be able to go to the other side of the planet and not fall off.
" I enjoyed playing ... on the upper side of the planet." - Lol.