I do not find any information on a loss of their flag on Day 1, but here are descriptions of Day 3

On the last day of the battle, the 26th were chosen to take part in the Pettigrew/Pickett's Charge on Cemetery Ridge, it was second from the left in the brigade's line. The 26th North Carolina suffered artillery fire and then small arms fire as it advanced. The regiment lost an additional 120 men, and the regimental flag was captured.
http://en.wikipedia.org/wiki/26th_North_Carolina_Infantry

……

the flag of the 26th (along with the 47th North Carolina who were beside them) were captured by the 12th New Jersey.

The 26th North Carolina at Gettysburg, July 3, 1863
http://twenty-sixthnorthcarolina.blogspot.com

…….

A sergeant and the color-bearer of the 26th made their way up the deadly slope until the defending Union riflemen from the 12th New Jersey, awed by this display of valor, held their fire to preserve the lives of such courageous men. The Northern soldiers allowed the two Confederates to approach closer, and then in a spirit of comradeship rather than enmity, called for the Southerners to cross the wall to safety. "Come over on this side of the Lord!" the Union defenders called to those two brave soldiers of the 26th North Carolina, still proudly carrying their battle flag.
http://www.gdg.org/Research/Authored%20Items/26th_nc.html