Kansas City, Kan. ? NASCAR is looking into reports that Kyle Busch and 65-year-old car owner Richard Childress were involved in an altercation Saturday after the Trucks Series race at Kansas Speedway.

Busch finished sixth, a spot behind Richard Childress Racing driver Joey Coulter after the two had a spirited late battle for position. Busch drove up beside Coulter’s truck following the race. When asked what happened between the two, Coulter joked that, according to the spotters, Busch was just congratulating him.

Busch is on probation through June 15 following a post-race, pit-road confrontation with RCR driver Kevin Harvick at Darlington. On May 24 in North Carolina, Busch was cited for careless and reckless driving, and speeding after driving 128 mph in a 45 mph zone.

Bill Janitz, a spokesman for Busch, told The Associated Press in an email that “there won’t be any comment tonight.” A phone message left for Richard Childress Racing seeking comment was not immediately returned.