‘Hands sticking to wheel’
After the session, with his helmet off but his mask on, Verstappen was more guarded.
"Just a mess with the traffic," he said before addressing the Hamilton incident in a bewildered tone.
"We're all lining up to go for our laps so I don't really understand what happened there."
Yet the afternoon was not a total loss for his team, which had been badly outpaced by Mercedes in the morning.
Red Bull's Mexican driver Sergio Perez was fastest with a time of 1min 34.946sec.
Lando Norris of McLaren was second 0.257sec behind.
Hamilton who had what would have been the fastest time of the session scrubbed out because he crossed the white track limits line on turn 19, was third 0.364, 0.50sec ahead of teammate Valtteri Bottas.
Daniel Ricciardo of McLaren, Lance Stroll in an Aston Martin and Ferrari's Charles Leclerc were the next three fastest, ahead of Verstappen.
"It was a good day," said Perez. "Obviously it's going to be very tight trying to put it all together and find those couple of tenths that would put us in the mix for pole tomorrow."
Perez said the real problem was not the heat.
"Very humid as well," said the Mexican. "My hands are sticking to the wheel a lot."
Mercedes dominated in the morning and Hamilton said changes the team made between sessions had not worked.
"We lost some ground or they gained some ground," he said. "It's been a good day but work to do."
Bottas faces a grid penalty on Sunday after Mercedes changed his engine for the fifth time this season.
After Hamilton took an ultimately costly ten-place grid penalty for an engine change before the Turkish Grand Prix, Bottas and two other drivers with Mercedes power units, George Russell of Williams and Sebastian Vettel of Aston Martin, are taking penalties in Austin.
Drivers are allowed three engines a season, after that they are hit with decreasing penalties. Bottas drops five grid places for his sixth engine. Russell and Vettel will drop to the back of the grid after each switched to their fourth power unit of the season.