Following the race, Gibbs bloodied Sam Mayer in a pit road fight that left a NASCAR official injured.
The two made contact on the final lap as they battled for position, which cost Gibbs the Dash 4 Cash $100,000 bonus and a top-five finish. Afterwards, he showed his displeasure with Mayer using both his race car and his fists. Both drivers were summoned to the NASCAR hauler after the incident.
Tuesday's fine is not in regards to the post-race brawl itself, but another action Gibbs took after the checkered flag flew. The penalty comes as a result of the 19-year-old making contact with another vehicle on pit road after the race, which is referring to when he ran into Mayer on the cool-down lap.
The violation fell under Section 4.3.A&E (NASCAR Member Conduct) and Section 8.8.8 (Crew member/Servicing) in the NASCAR Rule Book.
The No. 54 Joe Gibbs Racing team was also penalized $5,000 for an unrelated issue -- NASCAR found one unsecured lug nut on the car post-race.
Additionally, NASCAR has penalized the No. 2 Richard Childress Racing team of Sheldon Creed for a ballast violation. A piece of tungsten fell out of the car during NASCAR Xfinity Series practice. The violation falls under Section 10.5.2.5.F of the rule book and is considered a safety issue.
As a result, crew chief Jeff Stankiewicz, car chief Kris McCabe and engineer Sam Bowers have been suspended for the next four races.
There were no penalties for any Cup or Truck Series teams following the Martinsville race weekend.