They can't be original seats... they didn't have plastic seats back then. Maybe when they installed these seats they decided to have them be red seats for the reason you state, but these are not original 1950s vintage seats.
Originally Posted by Shotgun Shuba
This is home now - Citi Field, capacity 41,800 - and every seat in this ballpark seemingly filled, some standees as well, anticipating a piece of history as delivered by Mike Pelfrey, the 25-year-old from Wichita, Kansas. Into a windup, his first pitch in the history of Citi Field, a fastball for a called strike to Jody Gerut. Gerut off to a .214 start with no homers and one RBI. - Howie Rose calls the very first pitch thrown at Citi Field, April 13, 2009