U.S. Airways workers at Charlotte-Douglas International Airport discovered the hole early Monday morning or late Sunday night, WCNC-TV in Charlotte reported.
The plane had flown from Mexico to Denver, then to Charlotte.
The FBI, which is investigating, said there's nothing to indicate that terrorism is involved or that there was any malicious intent.
The aircraft was examined at the U.S. Airways hangar.
Agents don't know where it was shot, but experts said the bullet didn't strike a critical area because the pilots would have received a warning indicator if it had.
FBI agents said the bullet hole could be the result of a hunting accident.
Aviation consultant Alan Winninger said this case demonstrates that many airports have blind spaces where someone could shoot at an airliner and not be seen.
Puncture holes were found last December in a U.S. Airways jet at Charlotte-Douglas International Airport as it was sitting at the gate.
The FBI said it is still investigating the December incident and that nothing suggests the two incidents are related
