The Fort Worth Star-Telegram reports that Aledo High School coach Tim Buchanan learned of the online complaint against him Saturday, the day after his team beat Western Hills in a 4A matchup.
State law requires Aledo's principal to investigate the complaint and prepare a report.
Western Hills coach John Naylor told the paper he disagreed with the bullying allegation.
Buchanan, whose team is averaging 69.3 points a game on its way to a 7-0 record, pulled his starters after 21 plays.
The game clock ran uninterrupted beginning in the third quarter.
Aledo rushed for 391 yards and scored eight touchdowns on the ground.