Do lots of people get bulging abdomen, or is it unusual?

It depends: On what you mean by bulging. If it seems like there is liquid in there, that can be a sign of ascites, fluid in the abdominal cavity from conditions like liver disease. Of course, overeating can cause a lot of bulging, and obesity is quite common in the US.

Yes: Bulging can be many things from gas to bowel obstruction to fluid from heart, liver or kidney failure to hernia. Associated symptoms like fever, timing and pain will narrow the diagnosis. If it's problematic and doesn't resolve, get it checked out.