Fox Sports' Jay Glazer reported the NFL had began investigating after a Chargers equipment man was spotted hiding an illegal sticky substance and giving it to players. A line judge saw it, had it confiscated and sent to the Broncos and to the league, Glazer posted on Twitter.
The NFL banned the use of adhesive or sticky substances used to improve grip, such as Stickum, in 1981.
Chargers officials issued a statement regarding the reports that the NFL was looking into the possibility that the Chargers were using an illegal "sticky" substance.
"We are aware of the inquiry and are cooperating fully with the League," the statement read.
There is no word on what kind of penalty the Chargers would face if it is found that players used the substance during the game.