I had the same procedure, got hungry, just got up and ate a little. A cup of warm milk is filling and helps me get back to sleep.
Yes, some of it could be gas pain. I had lots of it for 9 months. Gas-X and all other meds did nothing for it. The pain and gas is mostly in the lower intestine, not the stomach. There is some stomach gas - we swallow air just talking - and it adds to the food gas. The only way to relieve gas is to eat non-gas-producing foods. Rice is good.