"As is the case after any race, we looked at a number of cars, including Robby Gordon's," spokesman Kerry Tharp said Monday. "Although we didn't find anything suspicious with the car at the time, we are continuing to review and discuss this situation."

NASCAR called for a caution about 35 laps from the finish of Sunday's race because a piece of roll bar padding was on the track. The timing of the caution severely hurt Jeff Burton, who was a lap down because of an earlier incident and needed the field to run through a final round of green-flag cautions to catch up.

Gordon, meanwhile, benefited from the caution because he was the first car not on the lead lap. That gave him NASCAR's "free pass" to get back on the lead lap, and he wound up finishing 10th.

Burton, a championship contender, finished 13th and demanded after the race that NASCAR investigate to determine where the debris came from.

"We were going to be OK and then they threw a caution because of a roll bar pad," Burton said. "NASCAR should stop every car on pit road and check for roll bar pads and whoever threw theirs out should be fined 185 points and $100,000 because it was a huge impact on the race.

"It is starting to happen just too often and NASCAR gets on everybody when it happens. Well, they should find out who did it and penalize them."

That led NBC to review its race footage, which appeared to show the debris came from Gordon's car. He denied throwing it.

"I definitely did not throw anything out of the window," Gordon told the network.

Now NASCAR is looking into the issue.

"What we saw at the time was debris on the race track, and for safety reasons, the caution came out," Tharp said. "We're gathering all the information we can and we'll make a determination based upon what conclusions we are able to draw from that."