Trahan and Gamez were at 13-under-par 131, a stroke ahead of Justin Leonard, the tournament's 2005 winner, who also shot a 64.
Trahan knocked in several long birdie putts in his round, finishing with just 23 putts for the 18 holes.
The putter has "been holding me back from becoming a better player," said Trahan, who was 171st in putting on the PGA Tour last year.
"Everybody knows a lot of guys hit the ball really well out here, but it's getting the ball in the hole that matters the most."
Gamez finished with 26 putts and Leonard sank birdie putts on his final two holes.