Yes, completely.
During the night, usually when laying down/sleeping, your body swells which can make for an uncomfortable night for some.
You may, sometimes, find that more parts will bloat, during the night.
No need to worry.
It's normal. My stomach was flat all until I reached about 25 weeks and every morning I would wake up with a little baby bump then it would sink back in and my stomach would be flat again during the day.